Anastasia Pavlyuchenkova survived a second-set scare to upset fourth-seeded Agnieszka Radwanska 6-4, 6-7 (4), 6-1 and advance to the quarter-finals of the US$2.4 million women's Rogers Cup on Thursday.

Pavlyuchenkova, seeded 16th, let two match points slip away while leading 5-4 in the second set and then lost the game on a double fault. But she rebounded in the third to extend her longest run ever at the hardcourt event.

"I think I'm still recovering from the second set," she said in a courtside interview. "Basically, I thought I had the match in my pocket and lost it, so I'm happy with the mental side."

Radwanska won the Rogers Cup the last time it was held in Montreal in 2014.

Fifth-seeded Simona Halep, a finalist last year in Toronto, bulled past 14th seeded Karolina Pliskova of the Czech Republic 6-3, 6-3.

The 24-year Romanian will next face Svetlana Kuznetsova, the ninth seed who downed 12th seeded Czech Petra Kvitova 7-6 (2), 6-3.

In men's play, France's Gael Monfils topped Belgium's David Goffin 7-6 (5), 2-6, 6-4.

Goffin lost the match when he put a backhand into the net, with Monfils pumping his fist in celebration on the grandstand court at York University's Aviva Centre.

Monfils will play the winner of the match between Canadian Milos Raonic and American qualifier Jared Donaldson in the quarter-finals.

"I love to play when it's crowded, and if the crowd is for the other one, it's fine," said Monfils, adding with a smile: "I expect a very good match."

Top-seeded Novak Djokovic was scheduled to face Radek Stempanek after Raonic's match on centre court.

Earlier in the day, second seeded Stan Wawrinka of Switzerland downed American Jack Sock 7-6 (3), 6-2.

Sock forced a tiebreak in the first set, even taking a 3-2 lead, but Wawrinka won four consecutive points to win the set.

Wawrinka put Sock away quickly in the second set, jumping out to a 4-0 lead and then serving out to win the match. Although Sock was only the No. 16 seed, Wawrinka doesn't take any of his opponents lightly.

"For me, it doesn't change much to be No. 2 seed, 3 seed, or 4 seed," said Wawrinka. "That's more or less where I have been the past two years now. At the end of the day, you need to beat those tough players."

Also, Japan's Kei Nishikori topped Rajeev Ram of the United States 6-3, 6-4 and South Africa's Kevin Anderson beat Australia's Bernard Tomic 6-4, 3-6, 6-4.

Wawrinka will play Anderson in Friday's quarter-finals and looks forward to the challenge of playing the six-foot-six South African.

"Tomorrow I'm playing against Anderson who I lost many times against him," said Wawrinka. "I lost two years ago when I played him here. It's going to be interesting match to play again against him. It's always been difficult to beat him, but hopefully I can do that tomorrow."