Ash Barty delivered the victory she needed on Thursday to earn a spot in the semis of the WTA Finals in Shenzhen. She is the first Australian to get this far at the season-wrap-up since Sam Stosur in 2010 and 2011.
The win in China sent the world No. 1 into the final four alongside holder Elina Svitolina, with the last two places still to be decided.
Barty came good through a 6-4, 6-2 defeat of Czech Petra Kvitova in 89 minutes.
But there were further crises as the toll of a long season began to weigh heavily con some competitors at the $14 million showpiece.
Bianca Andreescu became the second US Open winner to withdraw injured, with the Canadian teenager pulling out in the wake of a similar decision this week by Naomi Osaka.
The 19-year-old blamed the left knee problem which forced her to retire on Wednesday in her group match.
“I had a scan Thursday to check my knee after last night’s match, and unfortunately the results show that I need to withdraw,” Andreescu said.
“It was amazing to play here in Shenzhen at the end of this incredible season. I’m very disappointed to not be able to finish the year on my terms, but I am hopeful I will have more chances to play here in the future.
”The MRI just showed it didn’t look good enough to play. You’ve just got to take a step back, reevaluate.
“That’s what I did. I think this is the best decision for me right now.”
Alternate Sofia Kenin will replace Andreescu for the meaningless mast group march, playing on Friday against Svitolina.
Belina Bencic, last qualifier into the eight-strong field through her Moscow title, emerged a winner as exhausted and ill opponent Kiki Bertens quit their group match, trailing 7-5, trailing 7-5, 1-0.
Swiss success in the winner-take-all match sends Bencic into the semis after one hour of play.
Bertens, who earned a late place only this week when Osaka retired form the event, was seen by both the trainer and the doctor, who took her blood pressure on court.
Bencic came from a set down in the opener to win it.
Bertens has emerged as the Iron Woman of the week, playing her WTA-leading 81st match of the season after reaching the finals at the weekend of the WTA second-tier final in Zhuhai.
Barty gained some personal satisfaction from her third win over Kvitova, who held a commending 4-0 lead in their series at the start of 2019, Barty’s breakthrough season.
Thursday’s win was her first over the double Wimbledon winner Czech in straight sets, with Kvitova notching up 020 unforced errors in the opening set alone. Barty ended with 23 winners to 18 unforced errors.