TORONTO, Canada - It took nearly three hours and three rain delays, but former World No.1 Caroline Wozniacki scored her first-ever win over a reigning No.1 with a 7-5, 6-7(3), 6-4 victory over Karolina Pliskova in the quarterfinals of the Rogers Cup on Friday.

Wozniacki had previously been 0-6 in her career against No.1 players, with five losses to Serena Williams and one to Dinara Safina. 

"I thought she started off really strongly and she was attacking and playing really, really well," the Dane assessed. "After that, I feel like I stepped a little bit closer to the line just to try and take away a little bit of time. I once I kind of got on a roll, I started serving better.

"I just tried to stay steady, tried to take the ball on the rise and try to stay aggressive when I could and keep my serves aggressive too."

Though the Dane's spent a total of 67 weeks at the No.1 spot in her career thus far, she remained unaware of her winless streak against her peers while they've also held the top ranking. 

"She's had a great year and she's been playing really well. I don't really think about [beating a No.1] too much," Wozniacki said. "I knew I was going to play someone that was really tough today, and I'm just happy with my win and that's really it."

In a match that was delayed at the start due to rain, it was Pliskova who shook off the first delay with aplomb, as she won five of the first six games to take a commanding lead to begin the match.

However, Wozniacki soon found her feet, both literally and figuratively, as both players were forced to deal with two brief interruptions due to passing showers over the course of the ensuing games.

From there, the Dane dug in on defense, extending the rallies and working Pliskova over all parts of the court, as she won the last six games to steal the opener.

"I think the biggest mistake was in the first set - so because of that, I think I lost," Pliskova said. "Overall, I think the match was much longer than just the hours on the court. It's just tough to play her in these conditions. She's putting everything back, so obviously, I did some mistakes."

The 12 games of the second set went by without a break of serve, as Pliskova saved four break points in a crucial fifth game to stay ahead, and saved another with a big serve en route to a hold for 4-3.

Wozniacki in turn saved a pair of break points to hold for 4-4, and the duo dropped a combined three points on serve the rest of the way as the second set headed to a tiebreak. The No.6 seed was particularly effective on serve in the set, as she out-aced Pliskova with a total of six, and won 81 percent of points behind her first serve.

"It's just something I've really been working on, and it was really working for me today," Wozniacki said of her serve. "It was important in the match today, so I was very happy and pleased with that."

The World No.1 came up with her best in the tiebreak after letting an early lead get away, however, as she won the last four points - with two winners and a big forehand return on set point - to send the match to a decider.

Pliskova's offense and Wozniacki's defense went head-to-head in a tense decider, as both players found some of their best tennis to produce lengthy exchanges that thrilled the fans who waited out the rain with them. 

Nonetheless, it was Pliskova who looked as though she'd move towards victory as she grabbed the first break of the set in the fifth game, and moved two points away from a double-break lead with Wozniacki serving at 30-30 in the seventh game.

From there, Wozniacki refused to give in, and turned the match on its head by taking advantage of a double fault and three first-ball errors from Pliskova to break in the eighth game, as she ran off the last four games of the match.

"I just played one bad game when it was 4-3, serving, so that's it," Pliskova said. "I had new balls, was serving with the wind - it didn't help with the serve, and did some mistakes. I think the game was very open at 4-2, so if I would've broken her again - I think it was few good rallies where I could, you know, play different way.

"I think that was maybe the key in the third set because then, overall, I didn't play well, but she just put everything back, even my serves, even some of, you know, the groundstrokes. It was tough for me to close it."

Added Wozniacki: "I think I was maybe a little bit less tired towards the end. You know, I just kept hanging in there. I thought we both played a really good match. So I think mostly I think I was just -- I tried to keep steady also in the end."