Defending champion Elina Svitolina booked her place in the last four at the WTA Finals in Shenzhen with a straight-sets win over Simona Halep.
Svitolina overcame the Romanian 7-5 6-3 in one hour and 39 minutes to add to Monday's win over Karolina Pliskova in the Purple Group.
The Ukrainian's victory gave her some degree of revenge for the one-sided beating she suffered at the hands of Halep in this year's Wimbledon semi-finals.
And Svitolina insisted she was relishing the attention that comes with seeking to successfully defend the biggest title of her career.
She told media: "I don't take it as pressure to be fair. Of course there's some kind of pressure because you're losing (ranking) points, but I always take it like I've played well here before, so I can do it again."
Svitolina made a lightning start as she swept into a 3-0 lead but was hauled back by Halep, who then missed an opportunity to go a break up.
Gaining confidence on her own serve, Svitolina then grabbed her chance to take the lead when she broke Halep to love to win the first set.
Halep grabbed the first break in the second set, but Svitolina hit back twice and then survived two break points on her way to serving out for an impressive victory.
Bianca Andreescu will await the results of a scan on a knee injury before deciding if she can continue in the tournament after retiring midway through her match against Pliskova.
Andreescu required a medical time-out in the third game of the match after stretching for a point and was forced to retire after Pliskova took the first set 6-3.
The US Open champion said: "I stepped weirdly on a return - I heard my knee crack.
"Putting pressure afterwards on it really bothered me. I could barely bend my knee. But I fought with the pain as much as I could.
"At some point an athlete has to say 'stop' and just listen to their body. That's what I did."