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.
The sixth-seeded American pulled out, the WTA said on Wednesday, after a 6-3 6-3 defeat by Wimbledon champion Barbora Krejcikova on Tuesday ended her chances of qualifying for the last four in Riyadh.