World number one Novak Djokovic has pulled out of the Cincinnati Masters due to a wrist injury.

The 29-year-old Serbian had a disappointing Olympic Games in Rio de Janeiro as he was knocked out of the first round of the men's singles by Juan Martin del Potro.

Djokovic left the court in tears, but he suffered more woe a day later when he and his doubles partner Nenad Zimonjic were beaten in their opening match by Brazil's Bruno Soares and Marcelo Melo.

Now, the 12-time Grand Slam champion has announced that he will not play in Cincinnati, and will instead focus on being fully fit for the US Open in September.

"I am very sad to announce that I won't be able to play this year in Cincinnati at the Western & Southern Open Masters," Djokovic said in a statement. "I have a recurring injury that has taken its toll on my body due to a very busy and active schedule this year.

"I have played many matches and I have to take some rest in order to heal. I always have my hopes high on returning to Cincinnati and winning the only trophy I am missing in ATP Masters Series."

Djokovic suffered a shock third-round exit to Sam Querrey at Wimbledon in June.