MONTREAL (AFP) -- World number one Iga Swiatek outlasted a determined Danielle Collins 6-3, 4-6, 6-2, on Friday, Aug. 11, to book a semifinal clash with Jessica Pegula at the WTA Montreal Open.

Top-seeded Swiatek, whose fourth-round match on Thursday was spread over nine hours thanks to two lengthy rain delays, looked on the way to a quick win when she rode two breaks to a 5-1 lead in the opening set.

But Collins, the first qualifier to reach the quarterfinals of the event since 2019, found her range, winning two straight games before Swiatek pocketed the opening set.

Broken to open the second, the American broke back for 2-2 and broke again in the 10th game to force the third set.

From there, however, Swiatek was in control. She broke Collins for a second time for a 5-2 lead and claimed the victory on her third match point with a sizzling forehand winner.

"I really wanted to play powerful and I'm pretty happy that I managed to even increase the power in the third set," said Swiatek, who claimed her fourth career Grand Slam title at the French Open this year. "For sure, I was looking for that.

"Today I felt like I really needed to go even higher in terms of the intensity."

Fourth-seeded Pegula reached the semifinals for a third straight year with a 6-2, 5-7, 7-5 victory over her sixth-seeded doubles partner, Coco Gauff.

Nine double faults ultimately proved too much for Gauff to overcome -- two of them coming on break points in the third set.

"It's always tough to play your doubles partner," said Pegula, whose victory marked the end of a four-match skid against top-10 players.

"We know each other's games so well, so we kind of know what we're going to do to each other, know what our goal is.

"It's just kind of trying to execute it at the right times and as best as possible. So I think I was just able to do it a little bit better today."

Pegula gained the first break of the final set when Gauff coughed up her eighth double fault.

Gauff regained the break as she leveled the set at four-all. But a forehand and a backhand into the net in the 11th game gave Pegula a break chance and, after another double fault from Gauff, Pegula served it out with a love game.

Tough match for Gauff

"It was a tough match for me today," said Gauff, who was coming off her fourth WTA tournament triumph at Washington last week but saw her six-match winning streak halted.

"I started off a little bit slow, but I was able to turn it around a little bit for the second set.

"Then in the third I think I could have served a little bit better, been more aggressive in certain moments and less unforced errors, but Jess is not an easy player. If you don't hit a great shot, she's going to punish you for it."

The day started with a pair of third-round matches postponed from Thursday.

Liudmila Samsonova upset Australian Open champion Aryna Sabalenka, the second seed, 7-6 (7/2), 4-6, 6-3.

Samsonova was to return Friday night to face 12th-seeded Belinda Bencic of Switzerland in the quarterfinals.

Bencic was also pulling double duty, starting her day with a 6-7 (3/7), 6-3, 6-1 third-round victory over Petra Kvitova.

The winner of their match will take on either Daria Kasatkina or third-seeded Elena Rybakina for a place in the final.