MONTRÉAL, Canada - Unseeded and looming Aryna Sabalenka won a rematch of the Nature Valley International final on Thursday, knocking former World No.1, 5-7, 6-2, 7-6(4) to reach the third round of the Coupe Rogers after saving three match points.

"I was so happy," a breathless Sabalenka said after the match. "I was trying to play every point, without thinking of anything else. When you're on the court, you start thinking about a lot of things but none of the right ones. That was a big help for me."

Initially scheduled to play last night, Sabalenka and Wozniacki were delayed by an evening rainstorm and instead took the court on Thursday afternoon following a three-set thriller between Simona Halep and Anastasia Pavlyuchenkova. Sabalenka, aged 20, rallied from a 3-5 deficit in the final set before ultimately advancing in two hours and 31 minutes on court.

Sabalenka snapped a three-match losing streak that began after her breakthrough run in Eastbourne with a three-set win over Ana Bogdan earlier in the week. Enjoying a bright start on Court Central, she earned the first break of the match before Wozniacki flipped the script in much the same fashion as she did on grass, winning the final four games to take the first set.

"I learned that I had to serve well, because I had the chance to serve for the set in Eastbourne. That didn't work well in the first set, so I was a little disappointed, but I tried to keep staying in the game, taking my serves, and tried to be quiet. I did it, finally, so I feel so happy."

Undaunted, Sabalenka leveled proceedings with a mix of high-octane aggression and smart shot-making, the latter at the behest of new coach Dmitry Tursunov.

Wozniacki was playing her first match since Wimbledon and withdrawing from the Citi Open due to a right thigh injury, but said she felt physically healthy after the match.

The reigning Australian Open champion relied on all of her experience and athleticism to keep Sabalenka at bay at the start of the deciding set, twice holding serve in pressure situations and edging ahead 5-3 in the third.

A game from defeat, Sabalenka continued pressing as she gamely saved three match points and broke Wozniacki as she served for the match to level the set at five games apiece.

"I didn't win any of the match points," a disappointed Wozniacki said after the match. "I had an opportunity. I didn't get it.

"She plays very well, very aggressive. She serves big. I feel like I would have felt after the finals: it's obviously disappointing losing a match like this when you have the opportunity."

Wozniacki managed to force a tie-break but Sabalenka was in full flow by then, surging ahead 4-2 at the change of ends and securing victory on her first match point.

In all, Sabalenka struck a spell-binding 64 winners to 54 unforced errors, and saved seven of 10 break points - three of which were match points - throughout the match. Wozniacki stayed consistent with 17 winners to 22 unforced errors, but will likely rue her missed opportunities, particularly at the end of the match.

Up next for Sabalenka - in approximately 90 minutes - is Elise Mertens, whom Wozniacki beat in the semifinals of this year's Australian Open back in January. Avoiding the inclement weather that plagued Wednesday's schedule, Mertens overcame a second set hiccup to defeat Zhang Shuai, 6-2, 6-7(2), 6-0.

"This was a good warm-up for me!" Sabalenka joked. "I think I will be ok."