World number two Iga Swiatek will play Daria Kasatkina on Thursday in her must-win match to stay in the hunt for a spot in the WTA Finals semi-finals after Jessica Pegula withdrew from the tournament with a knee injury.

American star Coco Gauff defeated world No. 2 Iga Swiatek 6-3, 6-4 on Tuesday, sealing her spot in the semifinals of the year-end WTA Finals in Riyadh, Saudi Arabia.

Iga Swiatek and Coco Gauff are far from strangers. Swiatek had won 11 of their 12 matches before Tuesday's WTA Finals match. However, it quickly became clear that today's match would be more competitive.