World number one Simona Halep has withdrawn from the WTA Finals as she has not fully recovered from a back injury.
Kiki Bertens will make her debut in the end-of-season tournament in Singapore next week after Halep pulled out on Thursday.
The French Open champion sustained a herniated disc in a practice session at the Wuhan Open last month, but vowed to play in the WTA Finals.
Halep withdrew from the Kremlin Cup this week as she continues to be troubled by the injury and is taking no risks.
"The decision was tough for sure," Halep, who had flown to Singapore ahead of the tournament, told WTA Insider. "It's always difficult to withdraw from a big tournament. Actually, I think it's the first time in my life. So it was a tough decision but it's better for my health.
"Darren [Halep's coach Cahill] was 100 per cent to withdraw because he's worried about the back and it's better to put the health first, always.
"He always did that with me since we started. So he was more sure than me that we had to pull out. Then when I heard that he agreed with this it was easier for me to take the decision.
"My back is not okay. I didn't practice for the last four weeks. I'm not ready to compete at this level and I'm still sore. It's not easy to go on court and compete at this moment.
"It's the same back problem from Wuhan and I need a break to heal it. I need three to four weeks doing exercises and having a break and it should be fine. So I have enough time now to get ready for the off-season and to get ready for the next year."
Halep ends the season with three titles, including her maiden grand slam triumph at Roland Garros.
Bertens steps in for Halep as the world number 10 is ninth in the Race to Singapore.
|Warriors drop Hawks as Green serves suspension|
|In-form Healy sends Australia into semis|
|Former NBA star McGrady says Carmelo Anthony should retire|
|Celtics´ Smart: We have to look at ourselves in the mirror|
|Federer plays down preferential treatment talk|
|Mourinho is better than Guardiola – Maradona|
|Mbappe plays down Pele comparisons|
|Don´t worry bro – Mendy responds to Trump|
|Melvin, Snitker win manager of the year awards|
|Warriors´ Green suspended for Hawks clash|
|Asensio: It´s not for me to lead Madrid|
|Rooney ready to enjoy England farewell after pressure of ´Golden Generation´|
|Ludwigsburg stun high-flying Murcia in BCL|
|Rams v Chiefs moved to LA due to Mexico City field conditions|
|Skriniar discussing new Inter contract, confirms agent|
|Former Barcelona boss Martino named MLS Coach of the Year|
|Bell fails to report to Steelers, will sit out rest of season|
|Federer back on track after dismal Thiem display|
|Udinese appoint Nicola after sacking Velazquez|
|Monaco deny they broke rules regarding youth recruitment|
|Del Bosque, Zidane, Lopetegui - The former Castilla coaches Solari follows into Real Madrid hot seat|
|Ozil rejected ´crazy offers´ from Asia, reveals agent|
|Real Madrid appoint Solari on permanent basis|
|LeVert avoids need for surgery, should return this season|
|Neuer confident despite concerns over Bayern Munich form|
|All I ever wanted to do is win, says Sixers signing Butler|
|Pogba: Coming home to United was the best feeling ever|
|Watson among four signing new Bath deals|
|Susanna Dinnage to replace Scudamore as Premier League chief executive|
|Murray commits to Brighton until 2020|
|Rooney rejected chance of pre-World Cup farewell|
|Impressive Anderson thrashes Nishikori|
|Ozil´s Germany absence a ´pity´, says Sane|
|Rooney: I´ll finish my career in the US|
|McIlroy unsure of 2019 European Tour membership|
|Australian Open dismisses concerns of Federer scheduling bias|
|Hue Jackson joins Bengals staff as ´special assistant´|
|Real Madrid confirm Reguilon injury|
|Higuain handed two-match ban for Juve meltdown|
|Kruis ruled out for England as Jones calls up uncapped quartet|
|A year on from Italy failure, Ventura leaves Chievo after four games|
|Bairstow misses out as unchanged England promote Stokes|
|Recalled Alba denies Luis Enrique bust-up|
|´Unhappy´ Christensen won´t push for Chelsea exit|
|Nadal to make Abu Dhabi comeback in December|
|Taijul helps Bangladesh tighten their grip despite Taylor ton|
|Neymar joining Real Madrid wouldn´t hurt Iniesta|
|It´s just team spirit - Livingston not worried by Durant-Green exchange|
|Trippier out of England squad with groin injury|
|Ex-Sri Lanka international Lokuhettige charged by ICC|
|Former England and Chelsea star Joe Cole retires|
|Nets offer support to LeVert following serious leg injury|
|Panenka proud Sergio Ramos imitates his penalties|
|Liverpool´s Alisson seeks patience to reach potential|
|Anthony Davis leads Pelicans, Clippers hold off Warriors in OT|
|Lindelof rues international break for Man Utd|
|Shaqiri confident in more goals for Liverpool|
|Giants too good for 49ers in crunch time|
|Southgate named honorary Yorkshireman|
|Nicky Butt: Manchester United are low on confidence|
|Criticism of Barcelona star Dembele is overblown - agent|
|Thibodeau discusses Butler trade: We thought this was the best deal for us|
|Acuna, Ohtani win rookie of the year awards|
|LeBron James on Lakers’ early season struggles: ‘I almost cracked’|
|Welbeck has successful second operation on broken ankle|
|UEFA warns FFP cases can be reopened based on ´new information´|
|Foakes to keep England place for second Test|
|WATCH: Rooney looking sharp in England training return|
|Mbappe: Money in football is truly indecent|
|Djokovic back to brilliant best as Isner is beaten|