World number one Novak Djokovic pulled out of next week's China Open due to a continuing back injury. Djokovic, the winner of the Australian Open, Wimbledon and US Open in a remarkable year, suffered the injury during his unbeaten run at Flushing Meadows.
The Serbian attempt to play in his country's Davis Cup semi-final tie with Argentina two weeks ago but was forced to retire from his clash with Juan Martin Del Potro. His contribution in the Shanghai Masters which gets under way in two weeks' time is also in doubt.