World number two Maria Sharapova has pulled out of next week´s Rogers Cup in Toronto after suffering a right leg strain, tournament chiefs confirmed on Friday.
The Russian right-hander´s withdrawal was announced on the tournament´s Twitter feed, which added that Romania´s Simona Halep had now been elevated to second seed.
World number one Serena Williams will be chasing her fourth Rogers Cup crown after wins in 2013, 2011 and 2001.
Five-time Grand Slam tournament winner Sharapova, beaten by Williams in this year´s Australian Open final and the Wimbledon semi-finals, has never won the Rogers Cup.
The hardcourt tournament is one of several tune-up events leading into the US Open, where Williams will be attempting to complete a calendar year sweep of all four tennis Grand Slam events.