Jessica Pegula defeats Elena Rybakina in straight sets to open WTA ...

CANCUN, Mexico -- Jessica Pegula improved to 48-0 in 2023 when winning the first set, grabbing 10 of the last 12 games to beat Elena Rybakina 7-5, 6-2 in the opening match of round-robin singles competition at the WTA Finals on a windy Sunday night.

Neither woman had won a match previously at the season-ending championships for the women's tennis tour. Pegula went 0-3 in Fort Worth, Texas, a year ago, while Rybakina is making her debut appearance at the event for the top eight players in the world.

Top-ranked Aryna Sabalenka, who lost the 2022 WTA Finals title match to Caroline Garcia, collected the first 11 games and overwhelmed Maria Sakkari 6-0, 6-1 in Sunday's other singles match. Sabalenka is trying to become the first player since Serena Williams in 2013-14 to reach the final in consecutive years.

Sakkari is ranked No. 9 but moved into the field in Cancun when French Open finalist Karolina Muchova, who is No. 8, withdrew because of an injured right wrist.

Pegula, who is ranked No. 5, trailed by a break at 5-3, and Rybakina served for the opening set there. But Pegula broke and reeled off four games in a row to take that set. That put her in good position to win, given her success as a front-runner this year.

This was the tour-leading 42nd victory on a hard court this season for Pegula, a 29-year-old American whose parents own the NFL's Buffalo Bills and NHL's Buffalo Sabres.

Both women finished with 12 winners, and this was the key statistic: Pegula made only 16 unforced errors; Rybakina made more than twice as many, 35.

Rybakina is ranked No. 4 after winning Wimbledon in 2022 and finishing as the runner-up to Sabalenka at the Australian Open this January.

The WTA announced in September that it would be holding this tournament in Cancun under a one-year agreement. Some players, including Rybakina, raised concerns this weekend that the temporary court was not ready for practice until too close to the beginning of competition.

"This is something ... I'm not happy with. I'm pretty sure the rest of the players also [are] not happy," Sabalenka said.

"It's not great. I mean, usually we need like three to four days to kind of like adjust to the conditions. ... I hope that next year, WTA will do a better job," she said.