Top-ranked American Jessica Pegula triumphed in an up-and-down battle to reach the quarterfinals at the National Bank Open presented by Rogers on Thursday, ousting defending champion Camila Giorgi 3-6, 6-0, 7-5 in just under two hours.

No.7 seed Pegula fought back from a break down at 4-2 in the final set and saved a match point at 5-4 before collecting the topsy-turvy victory and improving to 6-2 against Giorgi. Despite it all, the match lasted a tidy 1 hour and 57 minutes. 

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Words from the winner: "The conditions were so tough ... and I knew it was just going to be a mental battle today," Pegula told WTA Insider after the match. "It's always a mental battle playing Giorgi, especially with the way she plays. She can be so hot and cold, so it was just a matter of mentally toughing it out."

"I'm always happy to get through a match like that. Of course, when you're playing it, you don't really want to do that. You don't really want to stress yourself out that much, but at the end of the day, those are the matches you have to pull through."

Flipping the script in Canada: Giorgi scored her first win against Pegula in 10 years in the semifinals last year in Montreal, where Giorgi swept to her first WTA 1000 title. But this time around in Toronto, Pegula emerged the victor, winning 78 percent of her first-service points and converting six of her nine break points. She rebounded after dropping an opening set where she was 2-0 up.

Pegula's sixth win overall broke a 2-2 head-to-head tie between the two on hard courts, and she's now 3-0 against Italians on the Hologic WTA Tour this year. 

Stat of the day: There's largely been no pattern to Giorgi and Pegula's eight career meetings. Thursday's affair was the fourth three-setter between the two, but only the second time that the winner of the first set did not win the match.

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All-American match denied: Pegula won't be facing her compatriot and Billie Jean King Cup teammate Alison Riske-Amritraj in her fifth quarterfinal of the season. Yulia Putintseva was a 6-3, 7-5 victor against Riske-Amritraj in their Round 3 contest, where she came from a break down in the second set. 

Putintseva, the Kazakh No.2 in the rankings behind Wimbledon champion Elena Rybakina at No. 46, leveled her overall head-to-head against Riske-Amritraj at 3-3 with the win. Her last win against her came in 2016, and the pair hadn't played in four years.

The match was won late in the second set: Riske-Amritraj led 5-3, and later, had 0-40 on Putintseva's serve at 5-4. At 5-5, she failed to convert three games points for 6-5 before surrendering serve for a sixth and final time in the match.

Pegula and Putintseva have never played.