(Reuters) - Belgian sixth seed Elise Mertens beat Maria Sakkari 6-2 3-6 6-1 in their round-robin match on Wednesday to end the Greek's hopes of making the WTA Elite Trophy semi-finals in Zhuhai, China.
Although Mertens was let down by her serve on several occasions with eight double faults, she converted seven break points.
Her final round-robin clash with Aryna Sabalenka is now a virtual quarter-final after the Belarusian beat Sakkari in straight sets on Tuesday.
"To win this match is actually a relief to play Aryna next, because you know if you lost the match in two sets or three sets it's another situation," Mertens told reporters, referring to the rules that decide who advances to the semis.
"So it's kind of a good thing that I won this match, even if it was in three sets. It actually doesn't really matter any more because Aryna won... in two sets."
One player from each of the four groups of three advances to the semi-finals.
In the other group, Ukraine's 10th seed Dayana Yastremska beat Donna Vekic 7-6(6) 6-2 without dropping serve to end the Croatian's run in Zhuhai.
Yastremska next faces top seed Kiki Bertens, who beat eighth seed Vekic on Tuesday, for a place in the semis.
In an all-American battle, second seed Sofia Kenin came away with a 6-4 6-4 win over seventh seed Alison Riske, who plays the Czech Republic's Karolina Muchova on Thursday in a must-win match to stay alive in the tournament.
(Reporting by Rohith Nair in Bengaluru, editing by Ed Osmond)