Novak Djokovic said he may have to skip his next tournaments in China next month, the Shanghai Masters and China Open in Beijing.
Newly crowned US Open champion Novak Djokovic may skip the Davis Cup semi-final singles rubber match opening on Friday between his country Serbia against Argentina due to exhaustion.
World number one Novak Djokovic had been leading 7-6 6-7 6-0 3-0 when his Serbian Davis Cup team mate Janko Tipsarevic, retired with a leg injury after three hours, 27 minutes of play at Arthur Ashe Stadium after feeling sharp pain in his left leg.
Novak Djokovic of Serbia beats Juan Martin del Potro of Argentina 6-3, 3-6, 6-3, 6-2 for his 40th straight victory this year.
Novak Djokovic defeated Rafael Nadal in the Madrid Open with a 7-5, 6-4 at the Caja Magica to extend his record in 2011 to 32 consecutive victories.