PARIS (Reuters) - Novak Djokovic pulled out of the Paris Masters on Friday because of a sore shoulder and apologised to fans who had bought tickets for his quarter-final showdown with French favourite Jo-Wilfried Tsonga. "Sadly I have to inform you that I have withdrawn from the tournament. I have pushed myself to the limit by playing, and after the match yesterday my shoulder got worse," the Serbian world number one said on his official website ( "I am very sorry for all of you who bought tickets and wanted to come and watch me play. My season has been long and tiring, I played all of my matches at my highest level, and now my body is aching for recovery." Djokovic 's body appears to have let him down following a remarkable season in which he won 10 titles, including three grand slams and five Masters crowns, to notch up a 69-4 win-loss record. The 24-year-old, who pocketed a $1.6 million bonus just for turning up in Paris by virtue of an ATP rule designed to entice top players to take part in the main events, now faces a race against time to get fit for the season-ending ATP World Tour Finals in London from Nov. 20-27. Having skipped the Shanghai Masters through injury, he suffered a recurrence of a shoulder problem in his semi-final defeat in Basel by Japan's Kei Nishikori last week. Djokovic 's withdrawal means the sixth-seeded Tsonga will take on either American John Isner, or Spain's David Ferrer, the fourth seed, in the Paris semi-finals.