LONDON - World No 1 Novak Djokovic clawed his way to victory over Tomas Berdych in his opening match at the ATP World Tour Finals on Monday, but Andy Murray's prospects look bleak after a groin injury flared up in his shock defeat by David Ferrer.

Djokovic, who arrived in London with question marks over his right shoulder, showed all the qualities that have made him the year's dominant force, digging himself out of trouble to win 3-6, 6-3, 7-6 (3) after saving a match point deep in the decider.

Murray, the hottest player in the world since the US Open, was tipped by many to win the title in London but after a 6-4, 7-5 defeat to bustling Spaniard Ferrer he faces an uphill battle to reach the semifinals even if he can continue.