Li Na beat Angelique Kerber of Germany 6-4, 6-3 Thursday to retain a slim chance of advancing at the WTA Championships.
Li's first win in two round-robin matches means she can still reach the semifinals, depending on other results in her Red Group.
The fifth-ranked Kerber, making her first appearance in the season finale, bowed out after losing all three of her matches.
She played more than three hours on Wednesday night in a three-set loss to No. 1 Victoria Azarenka.