Maria Sakkari is yet to lose a set through two WTA Finals games, defeating Aryna Sabalenka 6-2 6-4 on Wednesday to advance through the Nancy Richey Group into the final-four.

The first set was relatively smooth sailing for the Greek, taking advantage of Sabalenka's errors to break twice.

Belarus' Sabalenka did create some chances herself, with two break opportunities compared to Sakkari's four, but could not take either. She also committed the only two double faults of the opening frame, and had 13 unforced errors with her seven winners, while Sakkari had an even four unforced errors and four winners.

The second set was more of the same, with Sabalenka committing 16 unforced errors with only eight winners as Sakkari collected an early double-break to go up 3-0, seemingly coasting to victory.

But Sabalenka fought back, winning the next four games in a row to briefly take the lead in the set. Unfortunately for her, the see-sawing contest saw Sakkari rattle off the next three games to close out the win.

Sabalenka is still a chance to advance to the next round after defeating Ons Jabeur in her opening fixture.

WINNERS/UNFORCED ERRORS

Sakkari - 15/16

Sabalenka - 15/29

ACES/DOUBLE FAULTS

Sakkari - 1/1

Sabalenka - 0/4

BREAK POINTS WON

Sakkari - 5/7

Sabalenka - 2/7