Maria Sharapova has stepped out of Toronto with a right leg injury, raising questions about her fitness for this month's U.S. Open.

The world No. 2 has not played a match since losing to Serena Williams, 6-2, 6-4, in the Wimbledon semifinals on July 9th.

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Sharapova opened the season winning Brisbane then surged to the Australian Open final, falling to Williams.

In her last hard-court match, Sharapova was upset by 97th-ranked wild card Daria Gavrilova in her Miami opener last March. Sharapova has played only 10 tournaments this season.

Sharapova has failed to surpass the Rogers Cup round of 16 in her last two appearances. She lost to Carla Suarez Navarro in the round of 16 last summer and suffered a straight-sets loss to qualifier Galina Voskoboeva in the 2011 round of 16.