Venus Williams displayed a vintage performance to record her first win of the WTA Finals in Singapore against French Open champion Jelena Ostapenko.
Williams took three hours, 13 mins to beat 20 year old Ostapenko 7-5 6-7 7-5 in their White Group match at the WTA Finals on Tuesday.
Both needed a win to keep their fate in the season ending tournament after losing each of their first matches but it was Williams who emerged winner from the thrilling encounter which witnessed 21 breaks of serve with Williams getting 11 of the serves.
In the other game played, third seed Karolina Pliskova thrashed Wimbledon champion Garbine Muguruza 6-2 6-2 to become the first player to qualify for the semi-finals.
The Czech, needed just 62 minutes to beat the Spaniard to reach the semifinals with one game left to play.
Muguruza and Williams will play for the second qualifying place while Pliskova square off against French Open champion, Ostapenko on Thursday.
World number one Simona Halep plays sixth seed Caroline Wozniacki in the Red Group with a semi-final place up for grabs on Wednesday, before fourth seed Elina Svitolina and eighth seed Caroline Garcia try to keep their hopes alive.