Team Europe are on track for their fourth consecutive Laver Cup triumph after earning an early 3-1 lead against Team World.

Opening-day honours went to Bjorn Borg's Team Europe at TD Garden in Boston, where the defending champions moved into the box seat thanks to wins for Andrey Rublev, Matteo Berrettini and Casper Ruud in the singles on Friday.

John Isner and Denis Shapovalov managed to get Team World on the board in the evening's final doubles match against Alexander Zverev and Berrettini 4-6 7-6 (7-2) 10-1.

Roger Federer and Rod Laver were in the crowd as Team Europe – headlined by newly crowned US Open champion Daniil Medvedev and consisting of six of the world's top 10 – made a strong start courtesy of Norwegian Ruud, who overcame Reilly Opelka 6-3 7-6 (7-4), improving his career record to 3-0 against the towering American, and beating him in straight sets for the first time.

Italian star Berrettini then overcame Team World's Felix Auger-Aliassime 6-7 (3-7) 7-5 10-8 in the competition's longest match at two hours, 52 minutes.

Berrettini escaped with the second set after facing two break points in the penultimate game before prevailing against the Canadian in a thrilling match tie-break.

"One of the best matches bar none that I've ever seen played, absolutely just enthralling," said captain John McEnroe, whose Team World are eyeing their first Laver Cup trophy.

Rublev rallied past Argentina's Diego Schwartzman, who won the opening set and led 6-2 and 8-5 in the match tie-break before losing 4-6 6-3 11-9.

"Today we are a bit more lucky; Matteo won a tough match against Felix in a super tiebreak, now you saw my match," said Russian star Rublev.

"It was so close; Diego was leading all the super tiebreak, but in the end I find a way to win.

"This happens. This is tennis, this is sport. It’s emotions. Someone has to win, someone has to lose."

On day two, Stefanos Tsitsipas and Zverev headline the day session against Team World's Nick Kyrgios and Isner.

In the evening, Medvedev will meet Shapovalov before Rublev and Tsitsipas team up for a doubles battle with Kyrgios and Isner.

Nick Kyrgios, John Isner and Reilly Opelka have been named by Team World captain John McEnroe as his final three picks for the Laver Cup.

The trio join Denis Shapovalov, Felix Auger-Aliassime and Diego Schwartzman for the team event which runs from September 24-26 at TD Garden in Boston.

Laver Cup newcomer Opelka rose to a career-high world number 23 ranking en route to his first ATP Masters 1000 final in Toronto and defeated world number three Stefanos Tsitsipas, who will play for Bjorn Borg's Team Europe.

Isner, who has featured for Team World since the inaugural event in 2017, reached the semi-finals in Toronto and claimed his 16th ATP Tour title in Atlanta at the start of August.

He described the Laver Cup as "a highlight of my year", adding: "To be on a team with guys we're normally competing against is so different and so much fun. We come together so well as a group, the chemistry is awesome and it's such a great environment to be part of."

Australian firebrand Kyrgios is a striking inclusion in Team World's roster, while Team Europe will be without their big three: Roger Federer, Rafael Nadal and Novak Djokovic.

Federer and Dominic Thiem were expected to take part in this year's event, though both were forced to withdraw with injuries.

However, Borg's men still boast six of the world's top 11. World number two Daniil Medvedev leads the line-up, with Tsitsipas and Tokyo Olympics gold medallist Alexander Zverev for company.

Casper Ruud, who collected a 14th win in his last 15 completed matches on tour when he beat Opelka on Wednesday, will feature, while Andrey Rublev and Wimbledon finalist Matteo Berrettini complete the six-man team.

Team Europe have landed the title in each of the three editions of the tournament so far, with Prague, Chicago and Geneva having served as hosts.

Casper Ruud continued his excellent winning streak while Stefanos Tsitsipas made it a birthday to remember at the National Bank Open in Toronto.

Tsitsipas turned 23 on Thursday and marked the occasion with a 6-3 6-2 win over Karen Khachanov.

The Greek star was presented with a cake by tournament officials after his win, as the crowd serenaded him with a chant of 'happy birthday'.

It marks a significant improvement on when Tsitsipas turned 20. On that occasion, he lost the 2018 final of this event to Rafael Nadal.

Next up for Tsitsipas is Casper Ruud, who poked fun at his critics after he eased into the quarter-finals.

Ruud, the world number 12, won three titles on clay courts in July and has now continued that form in the ATP Masters 1000 event.

Playing on a hard court has proved no challenge for the in-form Norwegian, who wrote 'Hard Courts' with a smile underneath on the camera after his 6-4 6-3 victory over Dusan Lajovic on Thursday.

"I have seen a lot of people questioning my ability to play on hard court, so I just thought it was funny to write a little note," Ruud said in a news conference.

"I think it's fun to play on hard courts. Even though I (have achieved) most of my best results on clay, my best slam result is from this year’s Australian Open (where he reached the Round of 16), so I think it's a surface that also can suit my game well even though this year has been mainly clay.

“I think I'm motivated to come back to the hard courts. I have had two very good matches here. It's a great start for me to the hard-court swing."

Ruud, in the hunt for his fifth title of 2021, has won the only previous meeting between the duo.

"[I am] looking forward to that battle," Tsitsipas said. "We have played each other in the past. Not an easy guy to play against. Looking for a change, looking for a switch-up this time."

However, there was no place in the last eight for world number seven - and Olympic gold medallist - Andrey Rublev, who went down 7-5 7-6 (7-5) to American John Isner.

Fresh from a triumph in Atlanta, 36-year-old Isner has looked sharp all week and has now won eight successive matches.

It brings up a third quarter-final appearance for the world number 30 in Canada, and he will play French 11th seed Gael Monfils after he got past lucky loser Francis Tiafoe 6-1 7-6 (7-2). Monfils will be competing in his first ATP Tour quarter-final in 18 months.

Top seed Daniil Medvedev proved too good for Australian qualifier James Duckworth, winning 6-2 6-4 in one hour and eight minutes.

Medvedev was in ominous form on the hard court, sending down 10-1 aces and winning 27 of 32 points on his first serve.

The Russian world number two will play seventh seed Hubert Hurkacz who fought back to win 6-7 (7-9) 6-4 6-4 over Nicolas Basilashvili.

Eighth seed Diego Schwartzman lost in three sets to 10th seed Roberto Bautista Agut after the Spaniard saved three match points.

Bautista Agut will next play Reilly Opelka who came from behind, and also saved a match point, to win over Lloyd Harris in three.

Daniil Medvedev and Stefanos Tsitsipas survived three-set scares at the National Bank Open on Tuesday, but five-time tournament champion Rafael Nadal departed Toronto without even taking the court. 

Top seed Medvedev, who won just three games against Nadal in the final in 2019, the last time the tournament was played, prevailed 4-6 6-3 6-4 in his opener against Alexander Bublik.

The man Nadal beat to win the title the previous year, Tsitsipas, failed to convert on five match points in an epic second-set tiebreak but recovered to down Ugo Humbert 6-3 6-7 (13-15) 6-1.

Nadal pulled out ahead of a scheduled match against Lloyd Harris, who beat him last week in Washington as the 20-time grand slam winner struggled with a foot injury. 

Countryman Feliciano Lopez replaces Nadal in the draw and will face Harris on Wednesday. 

Elsewhere Tuesday, sixth seed Casper Ruud needed more than two hours to put away Marin Cilic 6-3 3-6 6-3, while 14th seed Grigor Dimitrov suffered a quick 6-3 6-4 exit against big-serving American Reilly Opelka.

A pair of unseeded veterans advanced, with 2016 finalist Kei Nishikori a 6-4 6-7 (5-7) 6-2 winner over Miomir Kecmanovic and John Isner defeating Alejandro Davidovich Fokini 6-4 6-1 in just over an hour.

Two days after appearing in his first ATP Tour final at the Citi Open, Mackenzie McDonald fell 6-3 6-4 to Benoit Paire in his Toronto opener. 

In other first-round matches, Karen Khachanov beat Cameron Norrie 6-4 5-7 6-4, Frances Tiafoe downed Yoshihito Nishioka 6-4 6-3, Dusan Lajovic handled Emil Ruusuvuori 3-6 6-3 6-3 and Nikoloz Basilashvili defeated Jenson Brooksby 2-6 6-0 6-4.

Casper Ruud captured his third title on clay in as many weeks after defeating Pedro Martinez 6-1 4-6 6-3 in the Generali Open final on Saturday.

The world number 14 continued his blistering form having also landed the Swedish Open and Swiss Open earlier this month.

The Norwegian has now won each of his last 11 matches since defeat by Jordan Thompson in the opening round at Wimbledon.

Ruud – also a winner at the Geneva Open in May – dominated the opening set against world number 97 Martinez, who was appearing in his first ATP final.

The Spaniard defeated second seed Roberto Bautista Agut on the way to reaching the showpiece, and responded well by taking a close second set.

Nevertheless, Ruud broke to take control of the decider, before closing out victory for a fourth ATP title of the season – all of which have come on clay.

Top seed Casper Ruud is through to his third successive ATP final after defeating Arthur Rinderknech at the Generali Open.

The world number 14 has been in incredible form on clay, having captured the Swedish Open and Swiss Open titles.

Ruud, who also landed the Geneva Open crown in May, has now won his last 11 matches, but was made to work hard for a 6-3 7-6 (9-7) victory over world number 91 Rinderknech in Kitzbuhel.

The Norwegian was forced to come from behind and defeat Sweden’s Mikael Ymer on Thursday, saving a match point in the process, and a single break swung a close opening set in his favour.

Fresh from defeating third seed Filip Krajinovic in the last eight, Rinderknech refused to lie down and took the second to a tie-break.

The big-serving Frenchman fired down 10 aces, but Ruud held his nerve to avoid a decider and prevail, saving a match point as he came from a mini-break down to extend his winning run.

The 22-year-old will play Pedro Martinez in the final after the Spaniard came from behind to beat Germany’s Daniel Altmeier 4-6 6-3 6-3.

Spaniard Martinez won 70 per cent of points behind his first serve and broke four times to move into the championship match.

Casper Ruud survived a scare as he progressed to the Generali Open semi-finals with a 3-6 7-6 (7-5) 6-1 victory over Mikael Ymer.

World number 14 Ruud is targeting a third successive ATP title, having also captured the Swedish Open and Swiss Open earlier this month.

It has been a timely return to form for the Norwegian, who suffered a shock defeat to Australia's Jordan Thompson at Wimbledon at the end of June.

Although he was in danger of seeing his nine-match winning streak come to an end in Kitzbuhel, after losing the opening set against Swedish opponent Ymer.

Ruud, who also triumphed at the Geneva Open in May, was then taken to a tie-break in the second ser by the world number 99, but held his nerve to tee up a decider.

It was one-way traffic from there with the 22-year-old dominating play to set up a last-four clash with Arthur Rinderknech, who hit five aces as he overcame third seed Filip Krajinovic 6-4 6-1.

Meanwhile, Daniel Altmaier's place in the semi-finals was secured with a 6-1 6-7 (5-7) 6-3 win over Gianluca Mager.

The world number 135, who reached the fourth round of last year's French Open, will play Pedro Martinez in the semi-finals after the Spaniard saw off Jozef Kovalik 6-2 6-2.

World number 16 Roberto Bautista Agut crashed out in the second round as the other favourites for the Generali Open battled through.

Bautista Agut lost the first set to Spanish compatriot Pablo Martinez in Kitzbuhel, Austria, and could not complete a comeback despite forcing a decider as he lost 6-4 6-7 (5-7) 7-5.

Top seed Casper Ruud, who won last week in Gstaad to claim his third ATP Tour crown of 2021 and fourth in total, came from 4-2 down in the first set to win 7-5 5-7 6-4 against Mario Vilella Martinez.

Third seed Filip Krajinovic survived a second-set scare to beat Carlos Taberner 6-3 2-6 6-4.

Arthur Rinderknech, who dispatched of fifth seed Federico Delbonis on Tuesday, awaits Krajinovic in the next round.

The other clash on Wednesday saw Sweden's Mikael Ymer cruise past home favourite Alexander Erler 6-2 6-3 to secure a quarter-final berth.

Ymer will now face the thankless task of challenging 22-year-old Ruud for a spot in the semi-finals.

Casper Ruud secured back-to-back titles by beating Hugo Gaston in straight sets to be crowned Swiss Open Gstaad champion on Sunday.

Ruud won the Nordea Open last weekend and added a fourth ATP Tour title of his career with a 6-3 6-2 defeat of Frenchman Gaston.

The Norwegian took his tally of tournament victories on clay this year to three, having also won the Geneva Open in May, and the 22-year-old will rise to ninth spot in the ATP Race To Turin on Monday.

Ruud saved nine of the 10 break points earned by first-time ATP Tour finalist Gaston, who only won 51 per cent of points behind his first serve.

Gaston, who had never been beyond the second round at an ATP Tour event before this week, was broken twice in each set as the 20-year-old was unable to halt Ruud's brilliant run on clay.

Left-hander Gaston broke straight back after Ruud went 3-1 up in the opening set but failed to back that up with a hold.

Ruud had as many as 16 break-point opportunities but got the job done in an hour and 34 minutes.

Hugo Gaston is one win away from securing his maiden ATP Tour title, but he must overcome in-form Casper Ruud at the Swiss Open Gstaad.

Gaston, ranked 155th in the world, booked his place in his first tour-level final with a 3-6 6-3 6-3 victory over Laslo Djere of Serbia on Saturday.

The 20-year-old had never advanced past the second round at an ATP Tour event before this week. He has now won three matches in a row in a third set.

"I tried to take more time with my game," Gaston said. "I made a lot of mistakes in the first set, so I tried to change my game. My serve was better in the second and third set.

"I am really happy to be in the final. It is going to be a good match, but I will try to enjoy [this] moment."

Ruud, meanwhile, enjoyed a rather more straightforward procession in his semi-final, with world number 249 Vit Kopriva little match for the 22-year-old Norwegian.

The world number 14 needed just 74 minutes to win 6-3 6-0, reaching his second final in as many weeks following his success in Bastad.

Ruud has won 23 clay-court matches already in 2021 and is in the hunt for his fourth career title.

Top seed Denis Shapovalov's Swiss Open Gstaad campaign came to an abrupt end as Vit Kopriva provided a second-round shock to eliminate the Wimbledon semi-finalist.

The world number 10, who has recently been praised by both Roger Federer and Rafael Nadal, took the first set 6-2 with ease before Kopriva, making his ATP Tour debut this week, emphatically fought back 6-3 6-2 to secure a memorable comeback victory.

Number three seed Casper Ruud battled past Dennis Novak 6-4 7-6 (7-5), while Benoit Paire, who only had two ATP wins in 2021 before the Hamburg European Open last week, was 6-4 to the good before Tallon Griekspoor was forced to retire due to injury.

Ruud, who has already won two ATP events in 2021 and three in his career, will now meet sixth seed Paire in the quarter-final stage.

But eighth seed Feliciano Lopez did not enjoy similar success as the world number 96 Mikael Ymer fought past the Spaniard to win 6-7 (6-8) 7-6 (9-7) 6-4 and set-up a quarter-final clash with Kopriva.

At the Umag Open in Croatia, third seed Filip Krajinovic breezed past Radu Albot to record a 6-4 6-2 win.

Krajinovic's countryman and number two ranked player Dusan Lajovic also went through with a 7-5 6-4 win against Bernabe Zapata Miralles.

Casper Ruud won his third ATP Tour title on Sunday thanks to a straightforward win over Federico Coria in the Nordea Open final.

The Norwegian needed just under 90 minutes to see off Coria, who was competing in his maiden tour-level final, getting the job done to win 6-3 6-3.

Ruud's electric start set the tone for the contest, as he raced into a 4-0 lead thanks to successive breaks – although Coria broke back to make it 4-1, his opponent's wobble was only brief.

Coria ensured the match was a little tighter initially in the second set, but Ruud's class showed as he rattled off three breaks on the trot and eventually converted his fifth match point in front of a joyous support.

"It was an incredible week, maybe the best week of my life," Ruud said after sealing the title without losing a single set.

"It's an incredible feeling playing here in Bastad with the Swedish, Norwegian and Danish support. There is nothing like that home crowd feeling.

"To win here means a lot. You get a little extra nervous as the No. 1 seed. Me and my father [former player Christian Ruud] have been joking about when I am going to beat him at this and this, and now I think I have beaten him in everything!

"The Ruud family can finally bring the trophy home to Norway. It is a special feeling having him here with me."

Filip Krajinovic will take on Pablo Carreno Busta in the Hamburg European Open final on Sunday.

A memorable week for Krajinovic continued as he saw off fellow Serbian Laslo Djere 6-4 6-2 in his semi-final.

Sixth seed Krajinovic defeated Stefanos Tsitsipas in the quarter-finals and ensured he followed up on that surprise victory with a dominant display against Djere on Saturday.

The victor committed only seven unforced errors in the match, while conceding just two break points in the contest.

Second seed Carreno Busta has not dropped a set all week and kept that run going with a 7-6 (7-2) 6-3 win over Federico Delbonis.

Carreno Busta needed just under two hours to see off a battling Delbonis, with neither player offering up a single break point in a first set that went the distance.

The Spaniard won five straight points to take the tie-break and continued that momentum into the second set when he broke Delbonis twice.

Neither Carreno Busta nor Krajinovic has ever won a tournament at ATP 500 level or above.

Carreno Busta has five career titles, but all of those are at ATP 250 level, losing to Dominic Thiem in his only showpiece appearance at this level at the Rio Open back in 2017.

Krajinovic, meanwhile, has lost all three of the career finals he has reached.

"I enjoy playing here, I feel comfortable here," Carreno Busta said. "It is my most important match this year on Sunday - I need to be really focused until the end.

"[Delbonis] is a really tough player and my level was very good. I probably played better in the second set, but I continued fighting all the time."

At the Nordea Open in Bastad, Sweden, top seed Casper Ruud was comfortable as he defeated Roberto Carballes Baena 6-1 6-4 to earn a place in the final.

Ruud needed just 79 minutes to do the job, breaking Carballes Baena on five occasions. 

He has only played two matches – both comfortable wins – to reach the final after a walkover against Henri Laaksonen in the quarters.

Rising star Ruud will bid for his second ATP title of the year and the third of his career against Federico Coria on Sunday.

Coria also had a comfortable last-four tie, seeing off Germany's Yannick Hanfmann 6-2 6 -1, with the win meaning the 29-year-old reached his maiden career tour final.

"I am very happy - it is my first final," said world number 77 Coria, who beat second seed Cristian Garin in the last eight.

"I played the best tennis of my life in this match. It is amazing here in Bastad, it is beautiful."