Jessica Pegula moved through to the third WTA 1000 final of her career at the Omnium Banque Nationale in Montreal with a 6-2, 6-7(4), 6-4 upset of World No.1 Iga Swiatek in Saturday's semifinals.

"It was a great match," Pegula said. "It was tough. Kind of a roller coaster. Really up and down, but I'm glad I was able to hold my nerve there at the end."

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Pegula was 0-2 in the semifinals in Canada before her 2-hour, 30-minute win against Swiatek, where she trailed 4-2 in the final set. Pegula had previously served for the match at 6-2, 5-4 in the second set, and led 4-2 in the tiebreak, before Swiatek forced the final set.

After losing four times to Swiatek in 2022, the American is now 2-1 against her this year. She was a 6-2, 6-2 winner against her at United Cup in January, where the U.S. team won the title. 

How the match was won: The match began with five straight service breaks, but nine straight points in Pegula's favor from 40-30 on Swiatek's serve in the fifth game put her on course to win her third straight 6-2 set against the World No.1. 

The second set was nip and tuck throughout. Swiatek led by a break twice, but Pegula earned herself an opportunity for another straight-sets win against her by winning four of five games from 3-1 behind. She failed to serve out victory, but the true turning point that sent the match the distance came three games later. 

With Swiatek serving down 4-3 in the tiebreak, having earned the mini-break back on the previous point, the song "Cotton-Eye Joe" piped through the in-stadium sound system mid-rally. Though it was soon rectified, chair umpire Marija Cicak was forced to call a let, and the point needed to be replayed.

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Pegula wouldn't win another point in the second set after that, and Swiatek in fact won 13 straight points from 4-2 down in the second-set tiebreak -- 12 of which came after the pause in play.

"I just thought it was funny," Pegula said. "I've never had that happen, let alone with 'Cotton-Eye Joe.' I was, like, is this really happening right now? Of all the songs. It was just, like, what is going on?" 

But at 4-2 down, having been broken twice in the final set, Pegula has one final surge: She won 16 of the last 19 points of the match to put a bow on the upset.

Pegula's key: "Even though I served for it at 5-4, I thought she played a great game," Pegula said. "She hit two lines and just went for her shots, and sometimes that just happens.

"Then in the third, got down to break. I was getting frustrated that I wasn't holding, but then at the same time I knew she was having trouble holding as well. It was whoever could kind of consolidate the break."

Swiatek debriefs: "She really pushed me, so I needed to change something up," Swiatek said. "It was working, but in the third, I don't really know what happened when I was leading. I've got to watch the match and analyze it, because for sure she was fighting for every point and I did as well. It was a tricky match."

Championship outlook: Pegula will look to be the first American to win the WTA 1000 in Canada since Serena Williams triumphed in 2013 against either No.3 seed Elena Rybakina or No.15 seed Liudmila Samsonova, who'll play their semifinal Sunday.