TORONTO • Caroline Wozniacki survived three rain delays to book her spot in the WTA Toronto semi-finals with a marathon 7-5, 6-7 (3-7), 6-4 victory over world No. 1 Karolina Pliskova on Friday.
The sixth seed posted her first career win over a No. 1 player in seven tries as she blasted eight aces in the 2hr 56min centre-court match.
She next faces American Sloane Stephens, who saved three match points in the third set to oust Lucie Safarova 6-2, 1-6, 7-5 in their quarter-final.
Pliskova, who had won two of her three previous matches with Wozniacki this year, fired five aces but won just 45 per cent of her second-serve points.
"I thought she started off really strongly and she was attacking and playing really, really well," Wozniacki said.
"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.
"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."
Wozniacki's record against No. 1s included five losses to Serena Williams and one to Dinara Safina.
Pliskova started quickly by winning five of the first six games of the first set which was delayed at the start by rain.
Wozniacki then asserted herself on defence and offence, moving Pliskova around the court to win six straight games to take the first set.
Pliskova never recovered from that first-set loss. From then, it was a matter of Wozniacki wearing her opponent down by keeping the ball in play.
"I think the biggest mistake was in the first set - so because of that, I think I lost," Pliskova said. "Overall, 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."
In Montreal, Swiss star Roger Federer outclassed Roberto Bautista Agut as he inched closer to his sixth title of the season in a 6-4, 6-4 win in the quarter-finals of the Montreal Masters on Friday.