Serena Williams
Serena Williams is a three-time winner at the Rogers Cup eventGetty

World No 1 Serena Williams has withdrawn from the Rogers Cup due to shoulder inflammation. Williams becomes the latest in a line of high-profile players such Andy Murray, Roger Federer and Rafael Nadal to opt out of the Toronto Masters.

Williams, a three-time Rogers Cup champion, was to receive a first round bye in the tournament that starts on 25 July. Her withdrawal has led many to wonder whether she will be fit in time for the Olympic games which start in two weeks' time.

"Due to inflammation in my shoulder, I unfortunately must withdraw from the Rogers Cup. I was looking forward to competing in Montreal and I look forward to returning soon," Williams said, as quoted by WTA Tennis.

The 34-year-old, who recently won her seventh Wimbledon crown to equal Steffi Graff's record of 22 Grand Slam titles, is in Stanford to cheer sister Venus. Serena was also seen practising, though the diagnosis of the injury is still uncertain.

Rogers Cup tournament director Eugene Lapierre was disappointed, but said he understood her decision considering the Olympics.

"Of course, we are disappointed that Serena will not play in the tournament this year. The fans really enjoyed the time she spent in the city in 2014. Because this is an Olympic year, the players have very full schedules. Sometimes your body needs rest. We hope that Serena will recover quickly and wish her much success for the rest of the season."

The withdrawal of Serena has led to rejigging of the women's singles draw with number three seed Garbine Muguruza taking up Williams's top spot.