Jessica Pegula beats No. 1 Aryna Sabalenka at the WTA Finals and clinches a spot in the semis

CANCUN, Mexico (AP) — As match point after match point came and went—there were six in all she didn't convert—Jessica Pegula made sure she stayed calm and didn't, as she put it, "freak out" against No. 1-ranked Aryna Sabalenka at the WTA Finals on Tuesday.

When her seventh chance to end things arrived, Pegula finally was able to complete a 6-4, 6-3 victory over Sabalenka in round-robin action at the season-ending championship for the top eight players in women's tennis.

"We all, as tennis players, have experienced that to some extent — on both sides. So, I mean, I try to use my match experience as best I can," said Pegula, a 29-year-old American who is now guaranteed to finish atop her group and reach the semifinals in Cancun. "Every match, you're always going to feel different. But I think the more you put yourself in those situations, the better you feel when they come up again. It doesn't feel like you have to panic as much."

In Tuesday's other singles match, 2022 Wimbledon champion Elena Rybakina beat Maria Sakkari 6-0, 6-7 (4), 7-6 (2). That eliminated Sakkari from semifinal contention and means Sabalenka will face Rybakina on Thursday for their group's second berth in the final four; that's a rematch of the Australian Open title match in January, won by Sabalenka.

Pegula has won both matches and all four sets she's played so far at these WTA Finals, a year after going 0-3 at the competition.

She had lost four times in a row to Sabalenka, who was the runner-up to Coco Gauff at the US Open in September.

On Tuesday, on a temporary hard court that has drawn criticism from Sabalenka and others, Pegula dominated for stretches. That included a four-game run in the opening set, and then a 4-0 start to the second while grabbing 16 of 19 points.

The big-hitting Sabalenka—who lost just one game on Sunday against Sakkari—finished with more than twice as many unforced errors as Pegula, including a 17-8 margin in the first set.

"I gave her too much," Sabalenka said.

The toughest portion for Pegula was at the end.

Serving for the match at 5-2, she got to 40-15 to earn a pair of match points. That's when Pegula double-faulted for the first time all evening, and followed immediately with another. Soon enough, Sabalenka had broken her.

In the next game, Pegula got to love-40—three more match points. And Sabalenka saved each of those, the first two with backhand winners, the next with a forehand winner. A sixth match disappeared when Pegula netted a forehand.

Soon enough, though, Sabalenka was faltering, double-faulting, putting a forehand into the net to offer up a seventh chance for Pegula to end the match, then framing a backhand to wrap it up.

"A really solid match—up until the couple of double-faults at the end. I mean, I felt like I was in control and playing smart and doing everything really well," Pegula said. "Sometimes you need to get through those moments to really test yourself. And so I'm glad I was able to overcome that challenge."