A cramping Novak Djokovic outlasted Czech Radek Stepanek in a titanic second-round battle at the US Open, winning 6-7 7-6 5-7 7-5 7-6 after four hours 44 minutes.
World number 35 Stepanek produced some outstanding tennis and Djokovic twice came from behind to earn a clash with Argentine Juan Martin Del Potro.
'I'd like to congratulate Radek,' Serbian Djokovic said. 'I really think he's a great player. We played a fantastic match today, unforgettable.
'I am totally exhausted. I have no energy. I smelt my shoes, they are so stinky but it's always good to win those matches.'
Stepanek, who slipped outside the top 100 after missing the second half of last year with a neck injury, kept Djokovic off balance with subtle changes of pace and superb volleying.
But Djokovic, a semi-finalist at the French Open and Wimbledon, levelled at two sets all and played a near-perfect final-set tiebreak, winning it 7-2.
Del Potro recorded a straight-sets defeat of number 31 Jurgen Melzer of Austria, 6-3 6-1 6-4.
Number eight Tommy Robredo of Spain had a tough time with American Mardy Fish, last week's Pilot Pen Championship runner-up.
Fish had the crowd on his side at Ashe and was 4-1 and 30-15 up in the fifth set before suddenly capitulating and losing 6-4 3-6 6-4 6-7 (7-9) 6-4.
