Rafael Nadal pulls out of Cincinnati Open

Rafael Nadal has confirmed that he will not play in next week's Cincinnati Open as he recovers from a knee injury.

The world number three has been forced to miss the Olympics and the Rogers Cup with the problem.

"I won't be playing at Cincinnati Open," he tweeted. "I am still not ready to play. I am continuing with my recup."

Nadal's withdrawal has cast doubt over his participation in the US Open, which starts on August 27 in New York.