World number one Andy Murray has withdrawn from the Cincinnati Masters because of an ongoing hip injury.
The Scot had previously pulled out of the Rogers Cup with the same injury, which hampered his Wimbledon campaign.
The 30-year-old could lose his number one ranking to Spain's Rafael Nadal and is a doubt for the US Open, which starts on 28 August.
"I'm continuing to work hard on the court with the aim of being in New York," said Murray.
"I won't be playing in Cincinnati as I continue my recovery - I always enjoy playing there and I look forward to returning next year.