Federer injured, Djokovic celebrates 4th ATP World Tour title

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ASTANA-LONDON. KAZINFORM - World №1 Novak Djokovic won his fourth title at the Barclays ATP World Tour Finals in London on Sunday without lifting his racquet, Kazinform has learnt from Vesti.kz. Swiss Roger Federer had to withdraw from the final match due to a back injury. "I'm not match fit to play the match tonight. Clearly I wish it wasn't so. I didn't want it to end this way," Federer said making the announcement of withdrawal to fans on court.