The world’s No. 2 ranked women’s player had arrived for practice on Wednesday but after a workout pulled out of the event.
“It’s disappointing for our fans and for all of us, but it’s part of the game, unfortunately,” said Eugene Lapierre, the tournament director, in a release. “Maria showed exceptional professionalism making the trip to Montreal, coming on site and try to practice, despite the face she had not been feeling well.”
Sharapova, who was Russia's flag bearer, may have been already showing the effects of the ailment last Saturday when she lost the Olympic final, 6-0, 6-1 to Serena Williams in London.
CBC Sports will have live coverage of the Rogers Cup on Saturday and Sunday.