Andy Murray has been forced to withdraw from the Western & Southern Open as his battle with a hip injury continues.

World number one Murray struggled with the issue prior to his Wimbledon defence and appeared to be suffering the effects when he was beaten in the quarter-finals by Sam Querrey.

The Brit has not played since that match and pulled out of the Rogers Cup, meaning he could well be replaced at the top of the rankings by Rafael Nadal this month.

However, Murray remains hopeful of being in condition to compete at the US Open.

"Unfortunately, I won't be playing in Cincinnati as I continue my recovery," Murray said in a statement.

"I always enjoy playing there and I look forward to returning next year.  I'm continuing to work hard on the court with the aim of being in New York."

Nadal will be the number one seed in Cincinnati while Roger Federer will be the second - the first time it has occurred at the Western & Southern Open since 2009.