Emma Raducanu's hopes of facing idol Simona Halep in the semi-finals of the Transylvania Open were brutally ended by a crushing defeat to Marta Kostyuk on Friday.

US Open champion Raducanu claimed her first ever regular WTA Tour win in Cluj earlier this week, with the 18-year-old keen to impress in the homeland of her father, but Kostyuk denied her the chance of a dream last-four clash with Halep.

The 19-year-old Ukrainian swept Raducanu aside in just 57 minutes, winning 6-2 6-1 as Kostyuk furthered her own burgeoning reputation in the game by reaching a third semi-final of the year.

Raducanu proved her own worst enemy, her 41 unforced errors more than double Kostyuk's 16, with the latter feeling confident as early as the first game when two double faults helped her break the Briton's serve.

"I don't know how I won the first game, I think that's where everything started," Kostyuk said. "I somehow won that game and I gained this confidence, like I'm not going to lose this match.

"After that, by the fifth game maybe, I figured out how to play her – today. Maybe next time I play it's going to be different tactics."

Top seed Halep enjoyed a similarly straightforward victory as she lost just two games en route to a 6-1 6-1 win over Romanian compatriot Jaqueline Cristian, a particularly impressive feat given she had been suffering with a back injury this week.

That success preserved Halep's 100 per cent record against fellow Romanians.

On the other side of the draw, second seed Anett Kontaveit was also an impressive winner as she disposed of Anhelina Kalinina 6-1 6-3 in just over an hour. Kontaveit has won 24 of her last 26 matches and will be the firm favourite against unseeded Rebecca Peterson, who beat Lesia Tsurenko 6-2 3-6 6-3.

At the Courmayeur Open in Italy, third seed Liudmila Samsonova cruised into the semis thanks to a swift 6-1 6-2 demolition of Anna Kalinskaya. She will meet Clara Tauson – seeded fifth – after the Dane came through a more gruelling 3-6 6-4 6-2 win over Ann Li.

The other semi will be contested by Donna Vekic and Jasmine Paolini, who were straight-sets winners over Wang Xinyu and Dayana Yastremska, respectively.

Top seed Andrey Rublev crashed out of the St Petersburg Open after a straight-sets defeat by Dutch qualifier Botic van de Zandschulp in the quarter-finals.

A recent US Open quarter-finalist, world number 69 Van de Zandschlup claimed the first top-10 win of his career on Friday.

The 26-year-old also advanced to the semi-finals of an ATP event for the first time.

There, he will face 2011 champion Marin Cilic, who was a 6-4 3-6 6-3 winner over third seed Roberto Bautista Agut.

Denis Shapovalov was another big-name casualty in Russia, the second seed going down 4-6 3-6 against world number 53 Jan-Lennard Struff.

Although, there were better fortunes for fifth seed Taylor Fritz. The Indian Wells semi-finalist is yet to drop a set this week after prevailing 6-4 6-2 against John Millman.

Elsewhere, Matteo Berrettini was the victim of another upset at the Erste Bank Open in Vienna.

The Wimbledon champion went down 1-6 7-6 (7-2) 6-7 (5-7) following a two-hour 40-minute battle with Carlos Alcaraz.

Reaching his first ATP 500 semi-final, the Spanish teenager claimed another big scalp having defeated Stefanos Tsitsipas at Flushing Meadows last month.

However, second seed Alexander Zverev remained on course for a fifth title of the season, as he claimed his 300th tour-level win.

The Australian Open finalist beat Felix Auger-Aliassime 6-4 3-6 6-3, avenging his fourth-round defeat by the Canadian at Wimbledon in July.

Alexander Zverev and Jannik Sinner moved into the quarter-finals of the Vienna Open on Thursday. 

Italian Sinner beat home hopeful Dennis Novak 6-4 6-2 to set up a tantalising showdown with Casper Ruud. 

Should he win that match, Sinner will move ahead of Hubert Hurkacz in the race to qualify for this year's ATP Finals, while victory for Ruud will strengthen the Norwegian's standing. 

"It's going to be tricky," said Sinner. "He's in a better position than I am for the race. I think right now it's tough to say and tough to do because in the end you try always not to think about that, but in the end you think about that because you believe." 

Zverev was given a sterner test, eventually overcoming Alex de Minaur 6-2 3-6 6-2 in one hour and 42 minutes. The Olympic gold medallist will now face Felix Auger-Aliassime, who fought back from a set down to defeat Cameron Norrie. 

Frances Tiafoe came from a set down to upset top seed Stefanos Tsitsipas 3-6 6-3 6-4 and earn a quarter-final meeting with Diego Schwartzman after the Argentine overcame Gael Monfils 7-6 (7-5) 4-6 6-2. 

In St Petersburg, home favourite and sixth seed Karen Khachanov lost a gruelling three-set encounter to Marin Cilic. 

The Croatian, who won the title in Russia in his last appearance in 2011, was 4-1 down in the deciding set but took all five of the final games to triumph after two and a half hours on court. 

"Everybody is playing good. The tournament is great. It's the end of the season, so everybody wants to finish on a great level," said Cilic, who next faces Roberto Bautista Agut. "For me, it was great to play this kind of a match today." 

Another Russian, Aslan Karatsev, fell to John Millman 6-3 6-2. Taylor Fritz and Botic van de Zandschulp also progressed in straight sets. 

Emma Raducanu is on course to face her idol Simona Halep for the first time in the Transylvania Open after they both advanced to the quarter-finals on Thursday. 

Raducanu celebrated her first WTA Tour win at the expense of Polona Hercog in Cluj on Tuesday and followed that up with a 6-3 6-4 defeat of Ana Bogdan. 

The 18-year-old US Open champion had a first-serve percentage of 69 and won 87 per cent of those points, breaking three times to move into the last eight. 

Third seed Raducanu said: "It's definitely taking me some time to find my feet still. I'm just taking some learnings from every match that I play. I don't think I'm the finished product yet." 

Next up for the Brit is a meeting with fellow teenager Marta Kostyuk after the sixth seed sent Mona Barthel packing with a 6-4 6-4 victory. 

Halep was troubled by a back injury in a 6-4 6-2 success over Varvara Gracheva in her homeland. 

The two-time grand slam champion played through the pain barrier, breaking twice in each set to progress, and could face Raducanu if she beats fellow Romanian Jaqueline Cristian. 

"The back got blocked and the pain is really big," Halep said in the on-court interview. "You cannot really bend much and you cannot move. 

"But sometimes you are used to the pain, I had this before many times, and I just wanted to continue and finish this match. It's good that I won this match, I don't know how." 

Anett Kontaveit, striving to secure a WTA Finals berth, extended her indoor winning run to 12 matches by seeing off Alison Van Uytvanck 6-3 6-4, while Rebecca Peterson knocked Irina Bara out in straight sets. 

In the Courmayeur Open, Jasmine Paolini came out on top 6-4 7-5 in an all-Italian battle with Lucrezia Stefanini and Zhang Shuai got past Wang Xinyu 7-6 (7-5) 6-4. 

The unseeded Donna Vekic also secured a place in the quarter-finals. 

Jannik Sinner continued his push for an ATP Finals spot with a straight-sets defeat of Reilly Opelka in the first round of the Vienna Open, while Carlos Alcaraz exacted revenge on Andy Murray.

Sinner won his fourth title of what has been an outstanding season for the Italian in Antwerp last weekend and is only 110 points adrift of Hubert Hurkacz in the battle for the final place in the season-ending event in Turin.

Murray did the 20-year-old a favour by knocking Hurkacz out of the ATP 500 tournament in the Austrian capital on Monday and seventh seed Sinner eased to a 6-4 6-2 win over American Opelka two days later.

Sinner, who will overtake Pole Hurkacz if he reaches the semi-finals this week, won 93 per cent of points behind his first serve and did not face a break point in a resounding win and will play Dennis Novak in the second round.

Murray beat Alcaraz at Indian Wells this month, but the 18-year-old rising star from Spain turned the tables on the three-time grand slam champion with a 6-3 6-4 second-round win in Vienna.

Former world number one Murray struggled with his serve and was broken five times as he made an early exit.

Third seed Matteo Berrettini beat Nikoloz Basilashvili 6-7 (5-7) 6-2 6-3 to reach the third round, while Diego Schwartzman, Gael Monfils and Lorenzo Sonego moved into the second round.

In the St Petersburg Open, defending champion Andrey Rublev beat Ilya Ivashka 6-4 6-4 to reach the quarter-finals along with Denis Shapovalov, a 2-6 6-3 6-0 winner against Pablo Andujar.

Jan-Lennard Struff also moved into the last eight, with Karen Khachanov and Marin Cilic securing first-round wins.

Simona Halep eased to victory over compatriot Elena-Gabriela Ruse on home soil in Romania to advance through to the last 16 of the Transylvania Open.

Ruse won her first WTA title at the Hamburg European Open in July and reached the final of the Palermo Ladies Open later that month, but she was second best against Halep.

The top seed produced a commanding performance as she held serve throughout and broke her opponent twice in both sets to progress 6-1 6-2 in a time of 73 minutes.

Halep, who departed at the quarter-final stage of the Kremlin Cup last week, is on course to meet US Open winner Emma Raducanu in the semi-finals in Cluj.

Anett Kontaveit also prevailed on Wednesday with a straight-sets win of her own, the second seed seeing off Aleksandra Krunic 6-3 7-5.

The 25-year-old, seeking her third WTA 500 indoor trophy in the space of two months, made the most of some Krunic errors to set up a last-16 tie with Alison Van Uytvanck.

Anhelina Kalinina earlier beat Anna-Lena Friedsam 6-2 6-2 to become the first player to book their place in the quarter-finals.

At the Courmayeur Open in Italy, top seed Dayana Yastremska required three sets to overcome Kateryna Kozlova 6-1 3-6 7-5.

Clara Tauson and Ann Li also avoided upsets as they beat Giulia Gatto-Monticone and Kamilla Rakhimova respectively.

Novak Djokovic's participation at the Australian Open has been cast in doubt once again as Victorian premier Daniel Andrews indicated the state that hosts the event will not welcome those who are not fully vaccinated against COVID-19.

Australian minister for immigration Alex Hawke revealed last week Djokovic, who has won a record nine titles at Melbourne Park, could only take part in January's tournament if he has received both jabs.

But the 20-time grand slam winner, who has declined to reveal his vaccination status, was given hope of competing after prime minister Scott Morrison said there would be exemptions should the state of Victoria – which includes Melbourne – agree.

However, responding to those comments on Wednesday, Andrews made clear his government would not apply for any sort of dispensation as it would not be fair on the other players and spectators who are fully vaccinated.

"The federal government manages the border and to the extent that anything the federal government says on this is clear, because their position has gone 180 from what the immigration minister said," Andrews said.

"What I'm making equally clear on behalf of every vaccinated Victorian who is doing the right thing... the only fair thing to do is to be very clear with every Victorian, my government will not be applying for an exemption for any unvaccinated player."

Recent reports suggested that over a third of professional players on the ATP Tour remain unvaccinated ahead of the 2022 Australian Open, which runs for two weeks from January 17.

Andrews added: "I'm not going to ask and actually require people sitting in the grandstand, people working at the event, to be vaccinated while players aren't.

"So we're not going to be applying for an exemption, so the issue is basically resolved."

Andrews also stated the same approach will be taken when Formula One returns to Melbourne in April next year.

Speaking last week, world number one Djokovic – who beat Daniil Medvedev earlier this year to win his latest Australian Open crown – told Serbian newspaper Blic: "Things being as they are, I still don't know if I will go to Melbourne.

"I will not reveal my status whether I have been vaccinated or not, it is a private matter and an inappropriate inquiry.

"Of course I want to go, Australia is my most successful grand slam tournament. I want to compete, I love this sport and I am still motivated.

"I am following the situation regarding the Australian Open... I believe there will be a lot of restrictions just like this year, but I doubt there will be too many changes."

Stefanos Tsitsipas survived a minor scare in the first round of the Vienna Open before ultimately going on to beat Grigor Dimitrov in straight sets.

It was neck-and-neck for much of the first set, with neither player losing serve, but Dimitrov appeared to have the upper hand when he got to 6-3 in the tiebreak.

Tsitsipas recovered emphatically, however, the top seed reeling off five successive points to win the set and he went on to book his spot in the second round thanks to a 7-6 (8-6) 6-4 victory. He will face Frances Tiafoe next.

"Grigor is a tough competitor and the level of tennis was really high today. We both competed at our highest [level]," Tsitsipas said afterwards.

"That was great tennis that was being played during the entire match and I got really close to my [best] offence and showed incredible attitude [in] the last game, which was the one that was the most crucial of the match."

Alexander Zverev, seeded second, was also made to work in his first-round clash with Filip Krajinovic.

While he blew the Serbian away in the first set, he found himself 5-2 down in the second as Krajinovic looked set to level the match, but Zverev scrapped his way back and then served to love to win 6-2 7-5. Alex de Minaur awaits the German.

Casper Ruud and Felix Auger-Aliassime, seeded fourth and sixth respectively, were two other high-ranking players who also secured progression, boosting their ATP Finals qualification hopes.

Ruud was pushed hard by Lloyd Harris but eventually outfought the South African in his 7-5 7-6 (7-2) win, while Auger-Alisassime made fairly light work of Ricardas Berankis 6-3 6-2.

Indian Wells champion Cameron Norrie, who is also in with a shot of reaching the ATP Finals, beat Marton Fucsovics 7-6 (7-4) 6-1 to set up a meeting with Auger-Aliassime – the British number one is 11th in the FedEx ATP Race to Turin rankings, one above his next opponent.

At the St Petersburg Open, fifth-seed Taylor Fritz was the highest-ranked player in action and he needed a little over an hour to beat Emil Ruusuvuori 6-1 6-4.

Pablo Andujar defeated Federico Delbonis to set up a meeting with second seed Denis Shapovalov, while Ilya Ivashka beat Laslo Djere for the right to tussle with tournament favourite Andrey Rublev next.

Emma Raducanu collected her first WTA Tour victory as she defeated Polona Hercog at the Transylvania Open in Romania.

Raducanu, who was the surprise US Open champion in September after not dropping a set throughout the tournament, appeared at just her fourth tour-level tournament and came to Cluj as third favourite.

The 18-year-old had lost opening-round matches at previous events in Nottingham, San Diego and Indian Wells.

However, world number 23 Raducanu finally recorded her first victory as she overcame a first-set scare to triumph over Hercog 4-6 7-5 6-1.

In the opening match of Tuesday's fixtures, sixth seed Marta Kostyuk cruised past Bernard Pera 6-3 6-4 to secure her last-16 berth.

Irina-Camelia Begu, ranked one behind Kostyuk for the tournament, did not enjoy similar fortunes as Romanian compatriot Irina Bara triumphed 7-6 (7-2) 0-6 6-4.

Jaqueline Cristian survived a marathon slog against Kaja Juvan as she came from a set down to win 3-6 7-6 (10-8) 7-6 (7-3) and book a second-round meeting with Ajla Tomljanovic.

Number one seed Simona Halep – who departed at the quarter-final stage of the Kremlin Cup last week – plays her first game on home turf on Wednesday against Elena-Gabriele Rusa and could meet Raducanu in the semi-final stages.

Meanwhile, Liudmila Samsonova, the third favourite at the Courmayeur Open, cruised past Stephanie Wagner 6-3 6-0 while seventh seed Jasmine Paolini comfortably dispatched Martina Di Giuseppe 6-4 6-1.

Shuai Zhang, who is the third seed in Italy, also enjoyed a routine victory as she eased past Jessica Pieri 6-1 6-3 after fourth favourite Petra Martic crashed out 3-6 4-6 to Saisai Zheng.

Jannik Sinner said he was "very proud" of the level he played at as he stormed to a straight-sets victory against Diego Schwartzman in the final of the ATP European Open on Sunday.

The number one seed continued his impressive form in the tournament by sweeping aside his opponent 6-2 6-2 in just 76 minutes.

Sinner was too powerful for his Argentine opponent and showed just why he is considered to be one of the rising stars of tennis with some breathtaking winners from all over the court in Antwerp, Belgium.

"I felt great on court. I moved well. I also served better, I think," the 20-year old said. "I felt great, but in tennis every day is different. You have to be careful. I think I played well the whole tournament, to be honest, from the first point to the last point.

"I like to play indoors. I tried to push the ball [through the court], which for me was important against Diego because he is moving very well. He's not missing so many shots. For me it was important trying to adapt the game somehow against him.

"I think I can be very proud about the level I played."

The top two seeds will do battle in the European Open final following commanding victories for Jannik Sinner and Diego Schwartzman on Saturday.

Sinner, the number one seed, moved into his fifth final of the season with a 6-2 6-2 defeat of Lloyd Harris in Antwerp.

The 20-year-old Italian, who is in the hunt for a maiden ATP Finals spot, dominated Harris from the baseline and saved all three break points he faced.

There were only 16 unforced errors from the racket of the composed Sinner, who will be bidding to win his fourth title of the season on Sunday.

Sinner said: "I am very happy to be in the final. I just love playing here and love playing indoors, so hopefully I can play a great match again tomorrow."

Schwartzman ended 20-year-old American Jenson Brooksby's impressive run with a 6-4 6-0 victory.

The Argentinian struck 15 winners and secured five breaks as he marched into the championship match.

Russian second seed Aslan Karatsev will come up against Marin Cilic in his first final on home soil after knocking compatriot Karen Khachanov out of the Kremlin Cup.

Karatsev beat Khachanov 7-6 (9-7) 6-1, while sixth seed Cilic – a two-time winner of the tournament in Moscow – got the better of Ricardas Berankis 6-3 6-4.

Anett Kontaveit will face Ekaterina Alexandrova in the Kremlin Cup final after maintaining her magnificent form with a straight-sets defeat of Marketa Vondrousova.

Ninth seed Kontaveit ousted Vondrousova in Moscow on Saturday with a commanding 6-3 6-4 victory.

The Estonian had lost both of her previous two meetings with Vondrousova, but needed only an hour and 14 minutes to reach her fifth final this year.

Kontaveit struck 26 winners, with her backhand a potent weapon, and broke five times – three of those coming in the first set after she failed to hold in the first game of the match.

The 25-year-old Tallinn native has lost only two of her past 22 matches, while her winning run indoors now stands at nine.

Standing in the way of Kontaveit and a fourth title in 2021 is home hope Alexandrova, who advanced to her first WTA 500 final when Maria Sakkari retired due to dizziness.

Alexandrova was leading 4-1 in the opening set when the fourth seed from Greece decided she was unable to continue.

There will be an unseeded champion at the Tenerife Open after Colombian Camila Osorio beat Camila Giorgi 6-4 7-5.

Ann Li will play in her second title-decider of the year courtesy of an emphatic 6-2 6-1 triumph over Alize Cornet.

World number one Ash Barty will skip the WTA Finals to focus on her preparations for the Australian Open and the 2022 season.

Barty won five titles in 2021, including a victory at Wimbledon that marked the second grand slam title of her career.

She reached the semi-finals of her home major in 2019 and her determination to go one better in 2022 has led Barty to call an early end to her 2021 campaign.

"I wanted to let everyone know that I won't be competing in any further tournaments in 2021, including the WTA Finals in Mexico," said Barty.

"It was a difficult decision but I need to prioritise my body and my recovery from our 2021 season and focus on having the strongest preseason for the Australian summer.

"With the ongoing challenges of travelling back to Queensland and quarantine requirements, I am not willing to compromise my preparation for January.

"I wish the WTA team and the players all the best for a successful WTA Finals and rest of the year.

"My focus is now on the Australian summer and doing everything I can to win the Australian Open.

"I can't wait to play at home again."

Jenson Brooksby enhanced his growing reputation and set up showdown with Diego Schwartzman in the European Open semi-finals.

The 20-year-old American, who took a set off Novak Djokovic and rattled the world number one at the US Open, is shaping up as potentially his country's biggest hope for the future in the men's game.

Californian Brooksby crushed Spain's world number 44 Alejandro Davidovich Fokina 7-5 6-0, and second seed Schwartzman awaits after the Argentinian took down another 20-year-old American, Brandon Nakashima, scoring a 6-4 6-2 quarter-final win.

Schwartzman is the man who ended Andy Murray's hopes at the tournament in Antwerp.

Brooksby, who had to win two qualifying matches to reach the main draw, said: "Tomorrow will be a great match. I'm really looking forward to it. I'll get some rest tonight and get ready to battle again tomorrow."

The other semi-final will see Italian top seed Jannik Sinner take on South African seventh seed Lloyd Harris following their respective straight-sets wins over Arthur Rinderknech and Marton Fucsovics.

There will be an all-Russian semi-final at the Kremlin Cup in Moscow, after Aslan Karatsev and Karen Khachanov won through to the final four.

Second seed Karatsev sank the hopes of Frenchman Gilles Simon, breaking serve five times on the way to a 6-4 6-3 win, while third-seeded Khachanov edged out Australian John Millman. A 7-5 7-6 (7-4) grind featured 19 aces by Khachanov, the 2018 Kremlin Cup champion, who saved four set points in the second set.

Marin Cilic thrashed Pedro Martinez 6-1 6-2 to set up a tussle with Ricardas Berankis, the Lithuanian ending Adrian Mannarino's run with a 6-2 7-6 (7-1) success. Frenchman Mannarino had stunned Russian top seed Andrey Rublev in the previous round.

Maria Sakkari admitted she got twitchy before finishing off Simona Halep to reach the Kremlin Cup semi-finals.

The Greek star is chasing what would be just her second career title at WTA level, but the limited silverware belies her growing reputation: Sakkari has shot up to a career-high seventh in the world rankings during her best season on tour.

Looking to finish with a flourish, both in Moscow and next month at the season-ending WTA Finals, Sakkari scored a 6-4 6-4 victory over former world number one Halep on Friday.

The victory sets up a last-four clash with Ekaterina Alexandrova, after the Russian impressed a home crowd by landing a 6-3 6-4 win against top seed Aryna Sabalenka.

Yet Sakkari was almost reeled in by Halep from the point of victory in the second set, being unable to finish off the match on her own serve after building a 5-1 lead. Halep twice broke back, before dropping her own serve.

"It was a very tough match today," Sakkari said in an on-court interview. "It was the first time I'd played Simona, but I knew what to expect: she makes a lot of balls, more than any other player. I had a tough moment in the second set when I was 5-1 up, but finally, I found a way. I got a little nervous, a little bit tired.

"The last couple of months have been tough, I've been travelling a lot so haven't recovered enough. I just tried harder in the last game and just went for it."

Alexandrova's shock win over Sabalenka gave her a sixth career victory over a top-10 player. Second seed Garbine Muguruza followed Sabalenka out of the tournament, walloped 6-1 6-1 by in-form Estonian Anett Kontaveit, who has won 19 of her last 21 matches on tour, including beating Sakkari in the Ostrava final last month.

Kontaveit's semi-final opponent at the WTA 500 event will be Marketa Vondrousova, who claimed a 6-4 6-2 win over Anastasia Pavlyuchenkova.

At the Tenerife Open, Italian Camila Giorgi is the only seeded survivor in the semi-finals. The Italian fourth seed saw off Arantxa Rus 6-1 6-1, with Frenchwoman Alize Cornet and American Ann Li also among Friday's winners at the WTA 250 tournament.