Lleyton Hewitt rolled back the years to send sixth seed Juan Martin del Potro crashing out of the US Open after securing a 6-4 5-7 3-6 7-6 (7-2) 6-1 victory.
Del Potro, who won the title at Flushing Meadows in 2009, recently pushed Novak Djokovic all the way in the Wimbledon semi-finals and was tipped by many as the man most likely to challenge the Serb, Rafael Nadal and Andy Murray.
But he ran into an inspired Hewitt, himself a former champion, who fought back from two sets to one down to complete a memorable upset in four hours and three minutes.
"I was pumped up when I won my first-round match because I knew I would be playing del Potro and it was a great opportunity to play on (Arthur) Ashe (Stadium)," Hewitt said.
"I don't know how many years I've got left in me, I keep getting asked that question. I just wanted to get out here and put on a great show.
"A couple of years ago I had a couple of foot surgeries and I didn't know if I would play tennis again. For me to be out here competing, it's a lot of fun. This is why I still play, to have moments like this."
Del Potro looked to have taken a decisive stranglehold on the match when he won the third set after Hewitt had served for a two-set lead.
The 32-year-old served for the fourth set as well, but he also squandered that opportunity before coming through to win what he later described as "one of the the best tie-breaks of my life".
Del Potro had been pushed hard by Guillermo Garcia-Lopez in the first round and he could not handle the energy of Hewitt in the fifth set, with the Argentinian double-faulting on the second match point.
Hewitt, now ranked 66th, has played some vintage stuff in patches in recent years but has not been beyond the fourth round at a grand slam since Wimbledon in 2009.
He will next face Russian Evgeny Donskoy for a place in the last 16.
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