World No. 2 Iga Swiatek came from behind to defeat Czech Republic's Barbora Krejcikova in an Orange Group singles opening match at the WTA Finals on Sunday in Riyadh.

Meanwhile, Coco Gauff won in straight sets against her American compatriot Jessica Pegula to secure her opening victory.

In the group's opening match, defending champion Swiatek faced recent Wimbledon champion Krejcikova. After dropping the first set and trailing 0-3 in the second, Swiatek managed to regain her form, fought back, and achieved a crucial break late in the set, taking it 7-5. Swiatek then maintained her momentum in the deciding set, ultimately winning 4-6, 7-5, 6-2.

"It wasn't an easy match, especially at the beginning, I was in trouble. So I'm happy that I managed to find some solutions and just get my game a little bit more solid," Swiatek said post-match.

In another match, third seed Gauff faced sixth seed Pegula in an all-American showdown. Gauff defeated Pegula in straight sets 6-3, 6-2, in a match that lasted 1 hour and 15 minutes.

In the doubles White Group matches, Gabriela Dabrowski and Erin Routliffe defeated Chan Hao-ching and Veronika Kudermetova 7-6 (6), 6-4. Meanwhile, Sara Errani and Jasmine Paolini made a comeback, beating Caroline Dolehide and Desirae Krawczyk 1-6, 6-1, 10-4.