Roger Federer will make a "last-moment decision" on his participation in next week's Laver Cup, according to fitness coach Pierre Paganini.

The 20-time grand slam champion announced on Thursday he will retire from top-level tennis after the tournament at London's O2 Arena.

However, Federer has not competed since Wimbledon 2021, after which he underwent a third knee operation.

And Paganini has cast doubt over whether the Swiss will be able to link up with the likes of Novak Djokovic, Rafal Nadal and Andy Murray in what is supposed to be his farewell event.

"This will probably be a last-moment decision," Paganini told Bilk. "He's practised at a level in order to determine exactly if playing is a good idea or not."

Federer is bringing down the curtain on a remarkable career that saw him win 103 ATP Tour-level titles – only Jimmy Connors (109) boasts more in the Open Era.

Among an array of other notable achievements, the 41-year-old spent a record 750 weeks in the top 10 of the men's singles rankings.

But Paganini says it "became clear a return to the Tour would be impossible" around July as injury problems took their toll on the all-time great.

In a more positive update, fellow coach Severin Luthi indicated Federer is on course to be fit to play at least some part in the Laver Cup.

"His aim is to play something, though whether it's singles or doubles we'll have to see," Luthi told Blick. "His aim is still to play at the Laver Cup – definitely.

"We train for three hours in the morning, then another two hours in the afternoon. He trained last week and is training again this week."

Wimbledon champion Elena Rybakina cruised to a straight sets victory over world number 65 Ana Bogdan to secure her place in Sunday's Slovenia Open final.

The Kazakhstan representative broke Bogdan five times while saving all eight break points to seal a 6-1 6-1 triumph and reach a first final since her SW19 victory over Ons Jabeur in July.

In the final, Rybakina will face Katerina Siniakova after she overcame Anna-Lena Friedsam.

Siniakova stormed to the first set, but the second was a much closer affair and the world number 82 watched five match points come and go before she finally clinched a 6-1 7-5 success.

At the Chennai Open, Magda Linette will play Linda Fruhvirtova in Sunday's decider after coming through semi-final encounters in differing fashion.

Third seed Linette raced out to a 3-0 lead in the first set over Katie Swan before the Brit called a medical timeout after just 16 minutes of play, eventually retiring with illness.

Fruhvirtova's semi-final was a much more gruelling affair, as the 17-year-old came from a set down to overcome Nadia Podoroska 5-7 6-2 6-4 and reach her first WTA final.

Andy Murray said it would be "really special" to get one last chance to share a tennis court with Roger Federer after the Swiss star announced his retirement.

The upcoming Laver Cup in London will be Federer's farewell event after he admitted defeat in his battle to overcome a knee problem.

Even Murray is unsure how much of an active part Federer will be able to play in London next week, but he would love to form a doubles alliance with the 20-time grand slam winner.

For many years, Murray was considered a part of a 'Big Four' in men's tennis alongside Federer, Novak Djokovic and Rafael Nadal. They were the quartet who dominated the latter stages of the grand slams and the most prestigious regular tour events.

It latterly became known as a 'Big Three' as Murray fell away due to injury, also proving unable to keep pace with the extraordinary major-winning standards set by Federer, Nadal and Djokovic.

Federer led the head-to-head 14-11 against Murray, with the Scot getting his biggest win over the Swiss in the 2012 Olympic Games final at Wimbledon.

Three-time slam champion Murray said of Federer: "Obviously he was an amazing player. I was lucky to get to compete against him in some of the bigger matches, in the biggest tournaments, on the biggest stages in our sport.

"At the time I probably didn't appreciate it as much but looking back it's pretty amazing. It's incredible what he achieved and also what Rafa and Novak have done as well."

Federer announced his retirement on Thursday, and while Murray said that marked "a sad, sad day for the sport", he was keen to celebrate "an unbelievable career".

There is an irony about Murray wishing Federer well in retirement, given Federer did likewise with Murray in January 2019, when it seemed the former Wimbledon and US Open champion was destined to hang up his racket. A new hip has allowed Murray to unexpectedly continue on tour.

Murray said of Federer: "The longevity he's had and what he did, the way that he played the game, conducted himself, all of those things. All of the players respected him for that.

"I don't know how much he'll be able to play [at the Laver Cup], I haven't spoken to him about that, but maybe I get to share a court with him in doubles or something like that, and that would be really special."

Qualifier Anna-Lena Friedsam backed up her victory over Emma Raducanu with a 1-6 7-6 (7-4) 6-3 quarter-final win over Diane Parry at the Slovenian Open.

After seeing off 2021 US Open champion Raducanu on Thursday, Friedsam continued her run with a superb comeback win to book her place in the semi-finals.

A rough start looked to have primed Friedsam for the exit door, but after prevailing in the second set, the 28-year-old pushed on to take herself within a match of a third career WTA Tour-level final.

She will have to wait to discover whether she will face defending champion Jasmine Paolini however, with the Italian's own quarter-final in Portoroz against Katerina Siniakova delayed until Saturday.

Third seed Elena Rybakina, meanwhile, will face Romania's Ana Bogdan after the Wimbledon champion was handed a walkover following Lesia Tsurenko's withdrawal.

Bogdan reached her second tour-level semi-final of the season by upsetting second seed Beatriz Haddad Maia, recording her 20th win over a top-20 opponent in the process, albeit her first since the 2018 Australian Open.

At the Chennai Open, 17-year-old Linda Fruhvirtova stunned Varvara Gracheva 6-4 6-3 to reach her first Tour-level semi-final.

Briton Katie Swan continued her impressive run with a 6-3 3-6 6-3 win over qualifier Nao Hibino and she will face Poland's Magda Linette, the highest-ranked player left in the competition, in the last four.

Fruhvirtova will go up against Nadia Podoroska, who came from a set down to defeat Eugenie Bouchard.

Carlos Alcaraz fell to a defeat to fellow youngster Felix Auger-Aliassime in his first match as world number one.

Alcaraz triumphed at the US Open on Sunday, beating Casper Ruud to clinch his first grand slam title and, in the process, become the youngest world number one since the rankings were first published in 1973.

The 19-year-old is the second-youngest male player to win the title at Flushing Meadows in the Open Era, and only the third player since the majors welcomed professionals in 1968 to win the US Open title at his first or second main draw appearance after Arthur Ashe and Rod Laver (in the first two editions of the tournament).

Yet back on home soil in Spain on Friday, Alcaraz was unable to claim victory in his first match since becoming number one, as he went down 6-7 (3-7) 6-4 6-2 to Auger-Aliassime in the Davis Cup Finals.

Canada's Auger-Aliassime did not concede a break point as he dragged his country level in their tie with Spain in Valencia, teeing up a doubles decider after Roberto Bautista Agut defeated Vasek Pospisil 3-6 6-3 6-3.

Auger-Aliassime, 22, has won both of his career matches against Alcaraz, after defeating him in the US Open quarter-finals last year.

Roger Federer "set the tone" for a new breed of tennis high achievers and his retirement brings time for reflection, his long-time rival Novak Djokovic said on Friday.

At the age of 41, battling knee trouble, Federer has decided to call it a day and intends to have a send-off on court at next week's Laver Cup.

Djokovic will join him on Team Europe for the match against Team World in London, with Rafael Nadal and Andy Murray also due to be involved.

An emotional finale to Federer's career is assured, in the city where he won eight Wimbledon men's singles title, just one of many records he established in a 24-year professional career.

Djokovic wrote on Instagram: "Roger it's hard to see this day and put into words all that we've shared in this sport together. Over a decade of incredible moments and battles to think back on.

"Your career has set the tone for what it means to achieve excellence and lead with integrity and poise. It's an honour to know you on and off court, and for many more years to come."

Djokovic holds a 27-23 head-to-head winning record against Federer, although their careers did not run precisely side by side, with Federer six years the Serbian's senior.

By the time Djokovic began to make a major impact on tour, Federer had arguably already hit his peak. From Wimbledon 2005 to the US Open in 2007, Federer reached 10 consecutive slam finals, a record that has not been matched.

He went past Pete Sampras' record of 14 majors in 2009, and Djokovic and Nadal have followed in his wake.

His longevity since has set a high standard for those two chief rivals, who have both recently edged ahead of Federer on the all-time list of men's grand slam singles title winners.

Federer won his 20th singles slam at the 2018 Australian Open, going closest to a 21st when he lost a thriller to Djokovic in the 2019 Wimbledon final, squandering two match points. Djokovic has 21, while Nadal leads the way with 22 titles.

Swiss great Federer retires with the most grand slam men's singles main draw wins in the Open Era (369), and as the only man to win 100-plus matches at two different slams (105 in Wimbledon and 102 at the Australian Open).

Addressing Federer, and pointing to his family, Djokovic added: "I know that this new chapter will hold amazing things for you, Mirka, the kids, all your loved ones, and Roger fans still have a lot to look forward to.

"From our family to yours, we wish you much joy, health, and prosperity in the future. Looking forward to celebrating your achievements and seeing you in London."

Serena Williams has paid tribute to retiring 20-time grand slam winner Roger Federer, describing her admiration for him and welcoming him "to the retirement club".

The 41-year-old confirmed on Thursday that he would bring an end to his illustrious playing career after the Laver Cup later this month.

Federer's announcement comes only weeks after 23-time major winner Williams declared her intention to step away from tennis, culminating at the US Open earlier this month where she bowed out in the third round.

The Swiss icon will bow out with 20 major titles to his name, a feat bettered by only two male players – Rafael Nadal (22) and Novak Djokovic (21). Williams sits behind only Margaret Court (24) for women's singles major titles.

"I wanted to find the perfect way to say this, as you so eloquently put this game to rest – perfectly done, just like your career," Williams wrote on Instagram.

"I have always looked up to you and admired you. Our paths were always so similar, so much the same.

"You inspired countless millions and millions of people – including me – and we will never forget. I applaud you and look forward to all that you do in the future.

"Welcome to the retirement club. And thank you for being you @rogerfederer."

Williams has deliberately avoided the use of the word retirement since declaring her intention to 'evolve' away from tennis, meaning the latter comment is of note.

The 40-year-old American has teased at a potential return to tennis, saying on Good Morning America this week that "Tom Brady started a really cool trend", referencing his decision to come out of retirement.

Both Lleyton Hewitt and Richard Gasquet used their media availability at the Davis Cup on Thursday to give their respect to Roger Federer after he announced his retirement on social media.

Federer, 41, won the first of his grand slams in 2003 at Wimbledon, and in that tournament it was Hewitt who was the reigning champion after becoming the youngest ever world number one back in 2001.

They came through in the same era, with Federer quickly overtaking the Australian as the sport's top attraction, and he would retain that mantle for over a decade as he and Rafael Nadal began their legendary rivalry.

Reflecting on their time on tour together, Hewitt called him "nearly unbeatable" as he shared his admiration.

"Yeah, he was from my kind of era, I guess," he said. "We were the same age, we grew up together in juniors. 

"I knew Roger extremely well and probably saw him slightly different to everyone else as well, because we grew up together. But he was the greatest of that time. 

"You know, obviously there are a couple of other guys now that are really putting their hand up, but he went clear easily from a grand slam perspective and really just his win-loss ratio [in the] mid-2000s era, he was nearly unbeatable. 

"It was pretty much only Rafa [Nadal] that could get him, especially on the clay. But most of all he's been a great ambassador for our sport. 

"I've always said that you don't want to push those guys out of the game too early. 

"Everyone wants to talk about retirement. When are they going to retire? You want to hold on to those greats. They've done so many special things for our sport. 

"But yeah, obviously, the body – you get to my age and his age now, and it's not easy. He's done everything in the sport that you could ever dream of."

In his own interview, Gasquet shared the sentiment, declaring "there is only one Roger Federer".

"It is a big shock – he is a legend of the game," he said. "It's not easy for anybody, I know it will be a big thing at the Laver Cup. I'm sure it will be wonderful there. 

"It's a tough loss for tennis. It will be different after that. It's still tennis, but it won't be the same without Federer.

"I was leading 1-0 against him [head-to-head], I won in Monte Carlo – but after that I lost maybe 20 times. I'm not the only one of course, it was incredible when I got to face him. 

"He is a legend of the game, everybody knows it. The technique, the charisma – everything was crazy. There is only one Roger Federer."

The greatest quarterback in NFL history took the opportunity on Thursday to pay his respect to fellow sporting icon Roger Federer after arguably the best player of his generation announced his retirement.

It is hard to imagine anyone will ever eclipse Brady's record seven Super Bowl wins, while Federer's mark of 20 grand slams will also likely stand the test of time as the new generation coming through share them around.

Brady, 45, is four years older than Federer, and gave retirement a go earlier this year before announcing his return 40 days later, so he knows exactly what kind of emotions Switzerland's greatest ever sportsman is going through.

When asked about his thoughts on Federer during Thursday's press conference, Brady shared his admiration.

"Phenomenal," he said. "Just a great player. He is just a great competitor and I think all those guys… we all work so hard. 

"We're all just working hard trying to be the best we can be at it, and he had a great run.

"He was great, always respectful of everybody and it meant a lot. He cared a lot. He maximised his opportunities. That's all we can all ask of ourselves."

Marion Bartoli says she feels "a sense of sadness" after Roger Federer announced his retirement from tennis, just weeks after Serena Williams' grand slam swansong.

Federer – a 20-time major champion – revealed on Thursday that he had made the "bittersweet decision" to end his glittering career, with next week's Laver Cup being his farewell tournament.

The announcement comes just over two weeks after Williams made her final slam appearance at the US Open, and 2017 Wimbledon champion Bartoli believes it represents "the end of an era" for the sport. 

When asked for her reaction, Bartoli told Stats Perform: "A sense of sadness, obviously, because we lost in the space of two weeks Serena [Williams] and Roger Federer who are basically two of the biggest stars that ever played the game, and two of the greatest who have ever played the game.

"I sense it was the end of an era almost because they have been part of my journey. When I was playing, Roger was obviously at his peak winning a lot of things and then Serena as well and now coming to see both of them taking their retirement almost at the same time.

"I feel like that book is almost closed, and now we are moving to the new generation of players with Carlos Alcaraz and all of them, but Novak [Djokovic] and Rafa [Nadal] are still hanging on.

"A sense of sadness obviously, but then completely understand his decision from what he had to face in the past three years."

Bartoli, who was also runner-up at the All England Club in 2007, thinks there are many players capable of challenging for the major titles in years to come.

Although, she does not see any player dominating tennis in the same manner as the 'Big Three' in Federer, Novak Djokovic and Rafael Nadal.

"I think our Alcaraz will very much be in the mix, but I don't think we will see one player being at 20 grand slams in 15 or 20 years, I don't believe it," she said.

"I think those three have been more than even superhuman. They've brought tennis to a level of consistency that, and along with Serena as well, I don't think anyone will be able to replicate that.

"When you see Carlos, he had an amazing US Open, just an incredible achievement. But Novak was not there, Rafa was injured, Roger doesn't play anymore, [Stefanos] Tsitsipas lost in the first round, [Alexander] Zverev can't play.

"It's just a lot of circumstances, and he had to save two match points against [Jannik] Sinner. So I don't see him dominating tennis as Roger did, or Novak did or Rafa did for the next 20 years, I just don't see it. 

"I think that the level between each other, it's very close. You don't see a major gap. So I think we'll have maybe Carlos winning one and then Sinner winning one, Zverev finally winning one and then Medvedev winning more.

"It's just going to keep rotating between maybe five or six names, but I don't think will be one name that keeps winning everything."

Roger Federer ranks among sporting greats such as Michael Jordan, Tiger Woods and Tom Brady.

That was the message from 2013 Wimbledon champion Marion Bartoli, who hailed Federer after he announced his appearance at September's Laver Cup would be his last in professional sport.

The 41-year-old won 20 grand slam titles across a legendary 24-year career, only Novak Djokovic (21) and Rafael Nadal (22) can boast more major crowns in men's tennis.

Federer has also won more men's singles main draw matches in grand slam tournaments than any other player in the Open Era (369), leaving behind a magnificent legacy as he prepares to step away from the court.

Bartoli has experienced retirement herself, having called quits on her career after a failed comeback from injury in 2018, and asked by Stats Perform whether Federer was a GOAT – greatest of all-time – Bartoli said: "Yes, he is very much in there – absolutely.

"Michael Jordan, Kobe Bryant, LeBron James, Tiger Woods, Tom Brady, they are people that transcend their sports – they are icons.

"You go in the streets, you say Roger Federer. I'm in Dubai right now [and if] you say 'Roger Federer' everyone would know who he is. And the same for LeBron and Michael Jordan.

"When you transcend your sport and you become an icon and everyone knows who you are, that's when you know you have been one of the greatest of all time across every sport.

"Same for Serena [Williams], you can put Novak and Rafa in there as well. But it's just that amount of fame and that amount of inspiring [the next] generation."

Having spent 237 consecutive weeks ranked as number one, Federer holds the record for the longest such streak in men's singles history after a four-and-a-half-year spell at the summit.

Federer was also present in the top 10 of the men's singles rankings for 750 weeks, an unmatched number for a male player since the rankings were first published in 1973.

Regardless of Federer trailing Djokovic and Nadal for grand slam titles, Bartoli believes the Swiss remains the best of the trio due to his elegant playing style.

"It's very much depending on your own taste in a way. If you like beautiful, elegant, smooth tennis you have to go for Roger Federer," she added.

"Now obviously with Novak having 21 and Rafa having 22 grand slams, if we speak numbers only then you have two players on top of him.

"But I think it's very much a debate because it depends on the style of play you like and, that said, I absolutely love to see Novak play and win.

"I absolutely loved to see Rafa winning again at Roland Garros this year, I think it was one of the most incredible sports achievements that you can possibly witness.

"But in terms of game style, and the way he has revolutionised tennis, I think Roger was the first one. And then they pushed each other to new heights and I think that was really special to see."

While many youngsters look to emulate Federer, Djokovic and Nadal, Bartoli highlighted the importance of Pete Sampras and Andre Agassi, too.

"You can tell how much impact a player [has] when you see a new generation trying to copy your style. I think Pete Sampras had that impact as well as Andre Agassi on the generation of Roger, Rafa and Novak," she continued.

"Roger has had that impact on the new generation with Carlos Alcaraz. So that's why I say that he was really the first one to elevate the game to another level because he brought that dimension of his forehand when he was really almost able to play the ball wherever he wanted.

"I always remember that sentence from Andre Agassi, when he started to play against Roger saying, 'well, I never felt against anybody that I had to play on a 20-centimetre square because that's the only safe spot I can play, which is deep to Roger's back. If I play anywhere, he will take the game away from me'. [Federer] was the first one to [do that] and then obviously Rafa and Novak arrived and sought to change that and they pushed each other to new heights.

"When you have the pinnacle of the 2008 Wimbledon final and all those matches in between them that was just beyond epic for me."

WTA world number one Iga Swiatek thanked Roger Federer for "everything you've done and everything you are for our sport" after the Swiss great announced his retirement.

Federer confirmed on Thursday that he would bring his illustrious playing career to a close after the Laver Cup.

The 41-year-old will bow out with 20 grand slam titles to his name, a feat bettered by only two male players – Rafael Nadal and Novak Djokovic.

Swiatek, meanwhile, won her third major title last week, defeating Ons Jabeur in straight sets to clinch the US Open, following her successes at Roland Garros in 2020 and earlier this year.

"I just want to thank you for everything you've done and everything you are for our sport," 21-year-old Swiatek tweeted in response to Federer's announcement.

"It's been a privilege to witness your career. I wish you all the best." 

Swiatek followed her post with a goat emoji, signifying that Federer is the greatest of all time.

Chris Evert, a former world number one, also joined the tributes to Federer, tweeting: "He was the epitome of a champion; class, grace, humility, beloved by everyone…and he elegantly mastered the sport like no other…Good luck to you, @rogerfederer don't go too far!"

Martina Navratilova, an 18-time major winner, posted: "What a heartfelt message, full of love, life, hope, passion and gratitude. Which is exactly how Roger played the game we love so much. Thank you thank you thank you, for all the magic!!!"

Emma Raducanu struggled with injury as she slumped out of the Slovenia Open in a second-round 7-5 0-6 6-3 loss to Anna-Lena Friedsam.

The 2021 US Open champion has faced an uphill battle on the WTA Tour this year and suffered another setback in Portoroz, where she was the top seed, playing the latter two sets with her left thigh strapped after a medical time-out.

A recovery looked possible when Raducanu cruised through a second-set bagel, yet the 19-year-old succumbed in the decider.

Raducanu's defeat follows a first-round exit at Flushing Meadows in a dismal attempt to defend her title.

Friedsman's win, meanwhile, secures the world number 213's first appearance in the quarter-finals of a Tour-level event since she lost in the final of the Lyon Open in 2020. It was also her second victory over Raducanu.

Diane Parry will face Friedsman in the last eight, after she overcame Anastasia Potapova, while Katerina Siniakova – who last week completed a career Grand Slam in doubles at the US Open – defeated Jodie Burrage.

Meanwhile, reigning champion Jasmine Paolini overcame a tie-break finale against Kaja Juvan. The Italian fought back to win 5-7 6-2 7-6 (7-5) to stay on course for a successful title defence.

At the Chennai Open, Anastasia Gasanova failed to back up her first-round win over top seed Alison Riske-Amritraj with another success, as Britain's Katie Swan edged her 7-6 (7-5) 6-2.

That sets up a quarter-final clash with qualifier Nao Hibino.

The top two seeds left in the competition, Magda Linette and Tatjana Maria, also progressed on Thursday.