TORONTO (AP) -- Serena Williams rallied from a rocky start to defeat Stephanie Cohen-Aloro of France 3-6, 6-4, 6-2 Tuesday night in the second round of the $1.3 million Rogers Cup tournament.

The fifth-seeded American, who hasn't played since Wimbledon because of an injured left ankle, struggled with her mobility on the court. She often failed to get to balls well within her reach and appeared to be favoring her left leg off and on throughout the match.

With the U.S. Open just over two weeks away, Williams is using this event as a much-needed tuneup for the final Grand Slam of the season.

Cohen-Aloro, ranked 91st in the world, broke Williams to open the match, but the American broke back then managed hold serve for a 2-1 lead. Cohen-Aloro then broke Williams again to take a 4-3 lead before breaking Williams a third time to win the set.

At that point, the crowd tried to give the star player a boost as shouts of "Go Serena!'' echoed throughout the Rexall Centre.

It must have worked.

Williams seemed to gain some confidence after going up a break in the second set, putting a little more pace on her serve and making fewer unforced errors.

Williams broke Cohen-Aloro to open the third set then broke her again to take a 3-0 lead and put the match out of Cohen-Aloro's reach.