Ailing Djokovic battles into quarter-finals

NEW YORK (Reuters) - An ailing Novak Djokovic battled past Spaniard Tommy Robredo 4-6 6-2 6-3 5-7 6-3 in an energy-sapping fourth-round clash at the U.S. Open on Tuesday.

The Serbian third seed, runner-up at Flushing Meadows last year, had treatment for a right hip problem and an upset stomach but somehow fought off Robredo in the fifth set to scramble into the quarter-finals.

Robredo, seeded 15th, deservedly won the first set but Djokovic hit back to win the next two, despite having treatment for a hip problem when leading 3-0 in the second.

Robredo then hit back from 3-1 down to force a decider, but Australian Open champion Djokovic dug deep into his reserves, breaking twice to clinch victory after three hours 45 minutes.

Djokovic will now play American eighth seed Andy Roddick or 11th seed Fernando Gonzalez of Chile.

(Writing by Simon Cambers, editing by Pritha Sarkar)