TORONTO (AFP) ― Wimbledon semifinalist Kirsten Flipkens shook off a slow start to beat Venus Williams 0-6, 6-4, 6-2 on Tuesday at the Rogers Cup, spoiling the seven-time Grand Slam champion’s return from injury.

Williams, sidelined by a lower back injury since her first-round French Open exit in May, was quick out of the blocks, pocketing the first set in half an hour.

Flipkens leveled the match with a break in the 10th game of the second frame, and once the 13th-seeded Belgian had forced the third set it was Williams who couldn’t keep pace.

Flipkens, who has been nursing a right knee injury and hadn’t played since falling in the Wimbledon semifinals to eventual champion Marion Bartoli of France, raced to a 5-0 lead in the third before Williams managed to hold serve.

Flipkens then surrendered a break, but broke Williams to seal the win and book a second-round match in Toronto with Dutch qualifier Kiki Bertens.

Williams said the ease with which she won the first set may actually have hurt her.

“I wasn’t expecting to play that well in the first set, so I think in the second I just didn’t handle it well,” Williams said. “Then I got down in the third ... I didn’t make the best choices out there all the time.”

Williams said she had only started practicing her serve more in the last week, and she expects it to improve before the U.S. Open begins later this month.

“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, who also praised Flipkens for hanging in.

“She definitely showed a lot of resilience by fighting back,” Williams said. “It’s never easy to lose a 6-0 set and come back.”

Slovakia’s Dominika Cibulkova became the first player to reach the third round of the $2.37 million tournament, shaking off a dismal first-set tiebreaker to upset eighth-seeded German Angelique Kerber 6-7 (7), 6-2, 7-5.