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.

Jessica Pegula’s late season rally has ended with the world’s No. 6-ranked player withdrawing from the WTA Finals because of a left knee injury. Pegula, who earlier this year rose to a No. 3 world ranking after reaching the U.

World No. 1 Aryna Sabalenka fell to Elena Rybakina 6-4, 3-6, 6-1 in the WTA Finals group stage on Wednesday. Sabalenka hasn't been eliminated from competition yet as she already clinched her group. It was a big upset as Rybakina is coming off two months of a break from tennis.

China's Zheng Qinwen reached the semi-finals of the WTA Finals in Riyadh after claiming an impressive 6-1 6-1 win over Italian fourth seed Jasmine Paolini on Wednesday. In her WTA Finals debut, the 22-year-old became the youngest player to reach the semi-finals since Petra Kvitova in 2011.

Elena Rybakina defeats World No. 1 Aryna Sabalenka at the WTA Finals, and Jessica Pegula withdraws with a knee injury.

There is not much left for Aryna Sabalenka to accomplish this season. Sabalenka has already clinched the WTA year-end No. 1 ranking to cap off her two Grand Slam titles. However, every match is important to Sabalenka.