MONTREAL (AP) — Jessica Pegula routed Liudmila Samsonova 6-1, 6-0 on Sunday to win the National Bank Open for her third career WTA Tour victory.

“We’re out on tour to win tournaments and to win titles every single week, but tennis can be really tough where you sometimes lose a lot,” Pegula said. “Even when you’re winning a lot of matches, you’re still not winning tournaments, so it can get tough. Winning a week like this week makes it all worth it and makes you want to keep going for more.”

Pegula, the 29-year-old from Buffalo seeded fourth in the tournament, topped Samsonova in 49 minutes after the 15th-seeded Russian beat third-seeded Elena Rybakina of Kazakhstan 1-6, 6-1, 6-2 earlier Sunday in a rain-delayed semifinal.

“I know, obviously, physically she wasn’t feeling her best, but at the same time I played a really clean match,” Pegula said. “I don’t really think I made any unforced errors or anything. I played kind of a perfect match.”

Pegula also won tour titles in 2019 in Washington and 2022 in Guadalajara. She is the first American to win the singles title in Canada since Serena Williams a decade ago, and the first to win in Montreal since Monica Seles in 1998.

Pegula won her semifinal Saturday, edging top-ranked Iga Swiatek 6-2, 6-7 (4), 6-4.

“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.”

Pegula beat Swiatek a day after fellow American Tommy Paul knocked off top-ranked Carlos Alcaraz in the men’s event in Toronto. U.S. players had not beaten the top-ranked man and woman in the same week since April 2008 in Miami when Serena Williams beat Justine Henin and Andy Roddick topped Roger Federer.

Both players struggled to hold serve, with Swiatek breaking Pegula eight times. They only won 11 of 30 service games combined.

“I was getting frustrated that I wasn’t holding,” Pegula said. “But then at the same time I knew she was having trouble holding as well. I was just like, `I know I’ll get more chances if I can just … hold.’ Basically, it was whoever could kind of consolidate the break.”

Rain forced the postponement of the night semifinal between third-seeded Elena Rybakina of Kazakhstan and 15th-seeded Liudmila Samsonova of Russia until Sunday. Early Saturday, Rybakina outlasted 10th-seeded Daria Kasatkina of Russia 5-7, 7-5, 7-6 (8) in a match that ended at 2:54 a.m.

Pegula, whose parents own the Buffalo Bills and Sabres, beat doubles partner Coco Gauff in the quarterfinals.

The 19-year-old Gauff won last week’s DC Open. Tied 5-5 in the third set, the sixth-seeded Gauff double-faulted for a ninth time while defending a breakpoint to give the sixth-seeded Pegula the edge. Pegula served out to improve to 2-1 in the rivalry and end a four-match losing streak against top-10 players. Gauff was coming off a victory Sunday in Washington.

“That was a good match,” Pegula said in her on-court interview. “It’s always tough to play your doubles partner — you know exactly what you’re trying to do. It just came down to the wire and who was going to compete better.”

World No. 1 Swiatek leads the tour with 50 match victories. The Polish star won the French Open in June and added her fourth title of the year last week at home in Warsaw.

“I kind of knew what I had to do to push her. Sometimes I could do that, sometimes I was making more mistakes — and I think that was the difference,” Swiatek said. “But I tried to play aggressively for the whole match.”

Pegula ended the match in 2 hours, 30 minutes, breaking Swiatek a final time after the top seed hit two shots long. Pegula had a chance to end the match much earlier, up 5-4 in the second set and serving, but Swiatek broke her serve to stay alive and took the set in a tiebreaker.

Pegula wondered if the service woes might have something to do with new balls. WTA players are testing out Wilson extra duty balls for the first time on hard courts this week, through next week and into the U.S. Open.

“I don’t know why this week all of us seem to be really having trouble, even girls that are considered the best servers on tour. It’s weird,” Pegula said. “It feels like the conditions, it’s flying a little bit, it’s swirling. I know it’s also the first week we’re playing with the Wilson extra duty balls.

“They’re a little bit heavier, so they’re not quite coming off the racket as well. Maybe we’re not used to it.”

Digital sports reporter Jonah Bronstein contributed.