Barbora Krejcikova defeated Coco Gauff to book her spot in the semi-finals of the WTA Finals and knock out defending champion Iga Swiatek.

The Pole needed less than an hour to dispatch alternate Daria Kasatkina, who had replaced the injured Jessica Pegula, 6-1 6-0 in the opening match of the day in Riyadh.

But her chances of progress depended on the second match, and her luck was out as Wimbledon champion Krejcikova battled to a 7-5 6-4 victory over Gauff, whose place in the last four was already secured.

All three women finished the group stage with two wins from three matches but Krejcikova, the lowest-ranked player at the tournament, topped the pool by virtue of the best sets percentage, with Swiatek the one to miss out.

Czech Krejcikova will take on Olympic champion Zheng Qinwen in the last four on Friday while Gauff meets world number one Aryna Sabalenka.

Krejcikova’s shock Wimbledon win was the outstanding high point of what has been largely a disappointing season for her.

But she has risen to the occasion in Saudi Arabia, bouncing back from a three-set defeat by Swiatek in her opening match by beating Pegula and Gauff, saving 11 of 12 break points on Thursday.

“Definitely this is a big win for me,” said the 28-year-old in her on-court interview.

“I’m really happy with the way that I played. Being able to quality for the Finals and also reaching the semi-finals, it’s something unimaginable before this tournament. I’m very proud of myself and I’m looking forward to the new challenges.”