Samantha Stosur extended her winning streak to six matches with a comeback victory over Israel’s Julia Glushko at the rich WTA Rogers Cup tournament in Toronto.

Coming off her confidence-boosting title win in California on Sunday, 12th seed Stosur was pushed before winning 5-7 6-2 6-3 on Tuesday night.

Next up she faces Spain’s Carla Suarez-Navarro aiming for a likely third round battle with world No.7 and defending champion Petra Kvitova as she gears for the US Open starting on August 26.

That assignment would seem less daunting after Stosur’s impressive wins over world No.4 Agnieszka Radwanska and world No.2 Victoria Azarenka in Carlsbad last week.

Wimbledon semi-finalist Kirsten Flipkens spoiled seven-time Grand Slam champion Venus Williams’ return from injury, inflicting a 0-6 6-4 6-2 defeat.

Williams, sidelined by a lower back injury since her first-round French Open exit in May, said she had only started practicing her serve more in the last week.

“Definitely today my service games I didn’t feel like myself, because usually I step up to the line, I go for it a lot. I didn’t really feel like I could do that today,” said Williams.

She expected it to improve before the US Open.

Slovakia’s Dominika Cibulkova became the first player to reach the third round by shaking off a dismal first-set tiebreaker to upset eighth-seeded German Angelique Kerber 6-7 (0-7) 6-2 7-5.

“It was a really tough match,” Cibulkova said. “Angelique, she’s putting everything back. Her defensive game is really good, and I just had to be patient and aggressive today. So it was not easy.

Cibulkova won the title at Stanford a fortnight ago, but suffered an early exit last week in Carlsbad.

In the day’s other second-round contest, third-seeded Radwanska beat Belgian Yanina Wickmayer 6-2, 6-3.