Li Na kept alive her chances of reaching the semi-finals of the end-of-season WTA Championships in Turkey, with a straight-sets victory over Angelique Kerber.
China's world No 8 needed just 85 minutes to see off Kerber 6-4 6-3 at the indoor court in Istanbul.
The result ended the German's slender hopes of qualifying for the last four, as Kerber lost her third successive match in Group A.
Kerber, who managed to win just a single set from her three ties, started strongly by breaking Na in her opening service game - before racing into a 3-1 lead.
However, Na hit back immediately by taking 10 of the next 12 games before failing to serve out for the match at 5-1 in the second set.
But when offered another opportunity in game nine, she made no mistake, winning to love and sealing the victory with her eighth ace of the afternoon.
In a match littered with 10 breaks of serve, the 30-year-old always held the upper hand as she notched her sixth victory in seven meetings over the left-handed world No 5.
Na, beaten in her opening match by Serena Williams, faces world No 1 Victoria Azarenka in her final group game on Friday and the winner of this tie will qualify for the semis.