TORONTO, Canada (AFP) — Simona Halep served twice for her match against Coco Gauff without success on Friday before finally securing a 6-4, 7-6 (7/2) quarter-final victory at the WTA Toronto Masters.

The former No. 1, a two-time winner in Canada, made hard work of her triumph over the rising American teenager who just missed a chance at cracking the world ranking top-10 for the first time.

Halep needed a second-set tiebreaker to advance into the semi-finals in just under two hours, lining up a meeting with seventh-seeded American Jessica Pegula.

Double Grand Slam champion Halep earned her 183rd match win at the Masters 1000 level.

Gauff fired a backhand into the net on Halep's first match point to end the encounter and lose her eighth straight set against the 30-year-old Romanian.

"I'm really pleased with the way I stayed strong mentally," Halep said. "I fought for every point."

"That was really important because she was doing the same thing. It's never easy against her."

On Saturday, Halep will play her 29th Masters semi-final against Pegula, who defeated Yulia Putintseva of Kazakhstan 6-3, 6-3.

It will be the first meeting between the two.

"It's going to be a big challenge to face a new opponent. It's always like that," Halep said. "But it's a semi-final. So for sure she's going to play good tennis. She's solid."

"I will focus on myself and I will just fight for the match as I do here every time."