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.

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. 

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.

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.

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."

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.

Maria Sakkari secured her place at this year's WTA Finals by progressing to the last eight of the Kremlin Cup in Moscow.

The third seed was on court for just 34 minutes on Thursday as last-16 opponent Anna Kalinskaya was forced to retire through injury at 6-2 1-0 down.

Sakkari has enjoyed a successful year on the WTA circuit, reaching grand slam semi-finals for the first time in her career at the French Open and US Open.

Through to the quarter-finals in the Russian capital, where she will play Simona Halep, the 26-year-old becomes the first Greek woman to qualify for the year-end WTA Finals in Mexico.

Eighth seed Halep beat Veronika Kudermetova 6-1 7-6 (7-4), while world number 35 Marketa Vondrousova also prevailed in straight sets against Ukrainian Lesia Tsurenko.

Elsewhere, Ostrava Open champion Anett Kontaveit is through to her eighth quarter-final of 2021 after defeating Andrea Petkovic 6-1 6-4.

Meanwhile, at the Tenerife Open, fourth seed Camila Giorgi enjoyed a commanding 6-1 6-2 victory over Montenegro's Danka Kovinic.

However, there was no joy for seventh seed Clara Tauson as the Danish teenager went down 7-6 (7-4) 2-6 6-4 against China's Saisai Zheng.

Aryna Sabalenka edged past Ajla Tomljanovic in the Kremlin Cup to reach the quarter-finals in her first match since contracting COVID-19 after the US Open semi-finals. 

Top seed Sabalenka – appearing in Moscow for the first time – had not played since being downed by Leylah Fernandez, having tested positive for coronavirus on the eve of the Indian Wells Open. 

The Belarusian, who sits second in the world rankings, profited from a bye in the first round before battling past Tomljanovic 7-6 (7-2) 4-6 6-1 on Wednesday as she fired 10 aces but made 30 unforced errors. 

Sabalenka will now meet Ekaterina Alexandrova after the Russian cruised past Anhelina Kalinina 6-4 6-1, while Anastasia Pavlyuchenkova comfortably defeated Bernarda Pera 6-2 7-5. 

Number two seed Garbine Muguruza also reached her seventh quarter-final of the season as she defeated Tereza Martincova 6-4 4-6 6-3 in just under three hours in Moscow. 

Meanwhile, Elina Svitolina was shocked in the Tenerife Open as she was dumped out by Maria Camila Osorio Serrano, who succeeded 5-7 6-3 6-2 to claim her first top-10 victory. 

Svitolina was the favourite in Spain and comfortably took the first set on Tuesday. However, inadequate light stopped play and the 19-year-old Osorio responded emphatically the following day to secure a memorable triumph. 

Ann Li coasted past Varvara Gracheva 6-4 6-2 after Anna Karolina Schmiedlova had dispatched Jaqueline Cristian 6-2 7-5 in the opening match of the day. 

Xinyu Wang retired injured against Alize Cornet, who led 4-1 in the decisive set, while Donna Vekic and Irina-Camelia Begu's match was suspended for bad light with the Croatian leading by a set. 

Simona Halep reached the second round of the Kremlin Cup on Tuesday with a straight-sets win over home hope Anastasia Potapova.

The former world number one, competing at the Moscow event for the first time since 2013, won 6-1 6-4 to set up a meeting with Veronika Kudermetova, who survived a marathon contest with qualifier Oksana Selekhmeteva.

Anett Kontaveit, who won the title in Ostrava last month, prevailed 6-3 6-3 against Katerina Siniakova. Another seed, Wimbledon quarter-finalist Ons Jabeur, retired against Ekaterina Alexandrova when trailing 6-1 1-0.

Andrea Petkovic also progressed when Jelena Ostapenko had to halt proceedings in their third set, while seventh seed Elena Rybakina lost in straight sets to Olympic silver medallist Marketa Vondrousova.

At the Tenerife Open, Camila Giorgi progressed past Aliona Bolsova 7-6 (7-4) 3-6 6-4 despite giving up two penalty games due to repeated indiscretions when line calls were called into question.

Fifth seed Viktorija Golubic lost in straight sets to Arantxa Rus, while Alison Riske was dispatched 6-1 6-4 by Donna Vekic.

Seventh seed Clara Tauson defeated Heather Watson via a final-set tie-break, while Varvara Gracheva won in the same vein against third seed Sara Sorribes Tormo in a match lasting nearly three and a half hours.

Top seed Elina Svitolina was one set up against Maria Camila Osorio Serrano when their match was suspended for the night.

Daria Kasatkina suffered a first-round defeat against Anhelina Kalinina in the Kremlin Cup, while Jaqueline Cristian stunned Tamara Zidansek at the Tenerife Open.

World number 28 Kasatkina, who has won four WTA Tour titles, fell on home soil to Kalinina as the Ukrainian triumphed 6-2 6-3 on Monday.

Ajla Tomljanovic cruised past Liudmilla Samsonova in similar fashion, claiming a 6-2 6-4 victory in Moscow to set up a last-16 clash with top seed Aryna Sabalenka, who is ranked second in the world.

Anna Kalinskaya joins Tomljanovic in the next round as she defeated Dayana Yastremska 7-6 (7-5) 6-4 on home soil and the Russian will now face French and US Open semi-finalist Maria Sakkari.

Lesia Tsurenko had no issues against China's Qinwen Zheng as she won 6-4 6-3, while American Bernarda Pera beat Aleksandra Krunic 7-6 (7-3) 6-3 to seal her second-round berth.

Meanwhile, number two seed Zidansek, who sits 33rd in the world rankings, crashed out in Tenerife as world number 108 Jaqueline Cristian succeeded 7-5 4-6 6-1.

Zhang Shuai was the sixth favourite in Spain but she lost to fellow Chinese star Wang Xinyu 6-2 6-1, with Anna Karolina Schmiedlova also defeating Kaja Juvan 4-6 6-1 6-4 and Irina-Camelia Begu overcoming Marta Kostyuk 6-4 6-4.

Paula Badosa denied Victoria Azarenka a slice of WTA Indian Wells Open history as the former world number one failed to become the first three-time winner of the singles event after defeat in Sunday's gruelling final.

Azarenka, also a winner in 2012 and 2016, had to come back from a set and a break down in the semi-final, and for a while looked like good preparation for the battle that Badosa provided.

But in the end Badosa prevailed 7-6 (7-5) 2-6 7-6 (7-2) after three hours, four minutes on court, securing only her second title in what was just her second final of the season while becoming the first Spanish woman to claim the title in Indian Wells.

A highly competitive start saw a combined total of nine break points go to waste in the first four games alone, and when Azarenka did finally lose a service game to go 4-3 down, she emphatically hit back at the first time of asking.

She had no option but to repeat that feat soon after when Badosa broke again to take a 6-5 lead, and she duly obliged to set up a tie-break.

But Badosa got the better of two-time grand slam champion Azarenka in the tie-break, despite the latter overturning a four-point deficit to go level at 5-5.

Azarenka appeared re-energised at the start of the second set, though, charging into a 3-0 lead inside 11 minutes, her level of intensity suddenly leagues ahead of her opponent's.

Badosa only showed brief glimpses of her ability and Azarenka had few issues levelling the match, her class on full display in the fifth game as she read a wide drop shot and replied with a sensational cross-court effort.

After such a colossal fight to get back on level terms it was perhaps to be expected that Azarenka would drop off a little early on in the decider, but a bad miss from Badosa allowed the Belarussian to recover from a break and she consolidated to tie the set at 2-2.

The pair continued to slog it out thereafter with neither woman giving an inch, Badosa's often-brutal power countered nicely by Azarenka's athleticism.

But Badosa was her own worst enemy as she overhit two shots to allow Azarenka to get what looked likely to be the decisive break, but the 32-year-old failed to serve out the match and, perhaps predictably, a tie-break ultimately beckoned.

Badosa's energy reserves suddenly looked far deeper than her opponent's as she moved her around the court with almost surgical precision, her eventual 7-2 win in the tie-break speaking to the ferocity she displayed to win the comfortably biggest title of her career to date.

Victoria Azarenka is one win away from becoming the first three-time winner of the WTA Indian Wells Open after rallying past Jelena Ostapenko in the semi-finals.

After dropping the opening set, two-time Indian Wells champion Azarenka stormed back to outlast the 2017 French Open winner on Friday.

Standing in the way of Azarenka and history is Paula Badosa, who eased past Ons Jabeur in the second semi-final in the Californian desert.

AZARENKA RETURNS TO INDIAN WELLS FINAL

Winner of the Indian Wells Open in 2012 and 2016, Azarenka is back in the decider thanks to a stirring 3-6 6-3 7-5 comeback against fellow seed Ostapenko.

Former world number one Azarenka was down a set and a break before the 27th seed fought back to prevail over Ostapenko in two hours, 20 minutes.

By seeing off 24th seed Ostapenko, two-time grand slam champion Azarenka celebrated her 33rd match win at Indian Wells – only two women have won more matches at the tournament, Lindsay Davenport (47) and Maria Sharapova (38).

"I think my season has been tricky," Azarenka said. "There were parts where I physically couldn't necessarily bring that extra level, extra fight, which was very frustrating. Then there were parts where I felt that I was looking for something to add, and I didn't necessarily know what it was. It was a lot of searching in the season, a lot of kind of stepping into unknown.

"I feel like right now I'm a bit more settled with a bit more structure, a little bit more discipline, which makes it not necessarily easier but a bit clearer what I need to do. So it doesn't take extra energy on that, so I can kind of focus my energy more on the fighting for every ball."

BADOSA UPSTAGES JABEUR

Spaniard Badosa added another scalp to her name by trumping 12th seed Jabeur 6-3 6-3.

Looking to become the first Spanish woman to win the Indian Wells Open, 21st seed Badosa made light work of Jabeur.

Badosa's success means she has beaten four top-20 opponents en route to the final, having stunned Angelique Kerber in the quarter-finals.

Having won her first title earlier this year in Belgrade, Badosa will feature in her second career WTA decider.

Angelique Kerber was knocked out in the Californian desert after a straight-sets quarter-final defeat to Paula Badosa at the WTA Indian Wells Open.

Badosa, who made this year's French Open quarter-finals, squandered two match points at 5-2 in the second set against three-time grand slam champion Kerber before steadying to secure her fifth final-four appearance of the season on Thursday.

In the semi-finals, Badosa will face Tunisian 12th seed Ons Jabeur, who got past Anna Kontaveit in straight sets, confirming her historic rise into the top 10 of the rankings, as the first-ever Arab player to achieve the singles feat on either the WTA or ATP Tour.

KERBER TOPPLED BY BADOSA

Former world number one and 10th seed Kerber bowed out at Indian Wells, with Badosa triumphing 6-4 7-5 in 86 minutes.

In her Indian Wells debut, 21st seed Badosa responded strongly after fluffing two match points to become the first Spanish woman to make the event's semi-finals in 18 years.

"It sounds amazing," Badosa said during her on-court interview. "The second set was very mental. I wanted this match so badly. I got super nervous.

"For one second I thought who was on the other side of the net and I got more nervous against a three-time grand slam champion. It means a lot to me. It's amazing."

In the first set, Badosa broke Kerber at 4-4 before serving out the opening set where she was excellent on her first serve, staving off the German's only two break points.

The Spaniard raced to a 5-2 lead in the second set and had two match points on Kerber's serve. The experienced Kerber responded by holding serve and then breaking back, before levelling at 5-5.

But Badosa showed her mettle by winning the final two games, breaking Kerber for victory as she upped her level.

JABEUR SEALS TOP-10 BERTH WITH TRIUMPH

Jabeur defeated Estonian 18th seed Kontaveit 7-5 6-3 to move into the top 10 for the first time in her career.

The Tunisian will become the first Arab player to make the top 10 when the updated WTA rankings are made official on Monday, but she also qualified for the biggest semi-final of her career to date.

"It feels amazing," Jabeur said. "We've been working hard since years. When I spoke at the end of last season, I said I wanted to be in the top 10. People doubted us as a team, we proved them wrong.

"Being a top 10 means a lot but we're not going to stop here. We're going to go further hopefully."

Jabeur, who made this year's Wimbledon quarter-finals, triumphed in 86 minutes, although she did not have it all her way, in a match full of momentum swings.

The 27-year-old Jabeur had been a double break up at 4-1 in the first set before Kontaveit hit back to level at 5-5, only for her to break back immediately and serve out the set.

Jabeur broke Kontaveit to love at 3-3, rattling off the final three games, including two breaks, to secure victory and keep alive her hopes of making the WTA Finals.

US Open champion Emma Raducanu has withdrawn from next week's Kremlin Cup.

Raducanu made history last month by becoming the first qualifier to win a major title with her triumph at Flushing Meadows, where she did not drop a single set all tournament.

However, the 18-year-old was beaten in her first match since that breakthrough success with a straight-sets loss to world number 100 Aliaksandra Sasnovich at the Indian Wells Open last week.

And Raducanu has now taken the decision to pull out of the Kremlin Cup in Moscow, which takes place next week.

In a statement released on Thursday, the Briton did not give a reason for her withdrawal but suggested she could return for the Transylvania Open later this month.

"Unfortunately I've had to make a tournament schedule change and won't be able to play Moscow this year, but I hope to compete there and in front of the Russian fans next year," said Raducanu, who is also due to compete at the Linz Open before the season is out.

"I look forward to returning to the tour in the next couple of weeks."

Speaking after her defeat to Sasnovich, Raducanu said she will need time to come to terms with her maiden grand slam triumph.

"I'm kind of glad that what happened today happened so I can learn and take it as a lesson. So going forward, I'll just have more experienced banked," she said.

"I think it’s going to take me time to adjust really to what's going on. I mean, I'm still so new to everything. I'm 18 years old. I need to cut myself some slack."