Defending champion Iga Swiatek was eliminated from the WTA Finals after Barbora Krejcikova defeated Coco Gauff to secure a place in the last four.

Swiatek had earlier needed less than an hour to defeat Daria Kasatkina, who replaced the injured Jessica Pegula in the day’s opening match in Riyadh, 6-1, 6-0.

However, her chances of progressing depended on the second game and her luck ran out when Wimbledon champion Krejcikova eked out a 7-5, 6-4 victory over Gauff, whose place in the semi-finals was already secured.

All three women finished the group stage with two wins from three games, but Krejcikova, the lowest-ranked player in the tournament, was at the top of the group on best set percentage, with Swiatek the one to miss out.

Krejcikova of the Czech Republic will face Olympic champion Zheng Qinwen in the semifinals on Friday, while Gauff will face world No. 1 Aryna Sabalenka. Krejcikova’s surprise victory at Wimbledon was the outstanding highlight of a largely disappointing season for her.

But she rose to the challenge in Saudi Arabia, bouncing back from a three-set loss to Swiatek in her opening game by defeating Pegula and Gauff and saving 11 of 12 break points on Thursday.

“This is definitely a big victory for me,” said the 28-year-old in her on-court interview. “I’m really happy with the way I played. Qualifying for the final and also reaching the semi-finals is something unimaginable before this tournament. I am very proud of myself and am looking forward to the new challenges.”