Stan Wawrinka's US Open preparations have been dealt a big blow with the news that he has been forced to withdraw from two upcoming events with a knee injury.
The World No 4 confirmed he has been forced to pull out of the Rogers Cup, as well as the Cincinnati Masters the following week.
Wawrinka's injury woes have left him without a match win anywhere in the world since reaching the French Open final in early June. That included a shock opening-round loss against Daniil Medvedev at Wimbledon.
"After much backwards and forwards and consultations with my doctors and my team, unfortunately I have decided to skip Canada and Cincinnati to be on the safe side, even though I've been battling hard to make these events," Wawrinka said in a statement released through his management company.
"Hugely disappointing for my fans and myself that I have to make this decision, but I need to be 100 percent confident before I resume competition till the injury that plagued me in Wimbledon has been resolved. My team and I are doing everything possible to make this a speedy recovery."
Rogers Cup director Eugène Lapierre said in a statement: "Stan has always been loyal to our tournament and we're obviously disappointed he won't be here this year.
"Stan is one of the best players in the world and we wish him a quick recovery and best of luck for the rest of the season."