Top-ranked Djokovic pulls out of Shanghai Masters

BELGRADE, Serbia (AP) -Top-ranked Novak Djokovic has pulled out of the Shanghai Masters because of a back muscle injury, further delaying his return to competition. Djokovic says he has not yet recovered from the injury he sustained in winning the U.S. Open and which he aggravated while playing for Serbia in the Davis Cup semifinals against Argentina. Djokovic says "I did another check this week and the results are not good. I need to continue my rehabilitation." The tournament in Shanghai starts Monday. Djokovic has already pulled out of the China Open in Beijing.