Djokovic battles past Robredo

Novak Djokovic was made to work hard but responded well to the test provided by Tommy Robredo to book his place in the US Open quarter-finals.

The third seed from Serbia lost the first set to the 15th-seeded Spaniard before battling back to win the fourth-round meeting 4-6 6-2 6-3 5-7 6-3 in an epic contest that lasted three hours and 44 minutes.