Former champion Juan Martin del Potro survived a scare to reach the second round of the US Open - however James Blake's career ended in disappointment.
Del Potro, the 2009 winner, needed four hours and 13 minutes to defeat Guillermo Garcia-Lopez 6-3 6-7 (5-7) 6-4 7-6 (9-7).
The sixth seed from Argentina roared with delight at the end after battling back from a break down to seal the win.
He said: "I felt good because I won a big battle for the first round.
"Of course, he's a very tough opponent. He played so solid on the baseline. We played every time long rallies. I had to make three or four winners in the same point to win the point.
"But it was really close for me. I think I was lucky maybe in the fourth set when I come back after being a break down. But I'm okay. I feel good with my level. My forehand was good. My serve improved since the last tournament. That's important."
While del Potro was relieved, Blake was left wondering what could have been as he let a two-set lead slip to lose to qualifier Ivo Karlovic.
The 33-year-old American announced on Monday that this tournament would be his last - and Karlovic sent him into retirement as he battled back to clinch a 6-7 (2/7) 3-6 6-4 7-6 (7/2) 7-6 (7/2) victory.
Blake, who reached number four in the world in 2006, said: "It's not ideal. I'm trying to have some perspective immediately after and think about the fact that it is just one match and it won't be the defining moment of my career luckily.
"It's not a fun way to do it, but only one guy's holding the trophy at the end of this two weeks. I wished it was me. I did everything to prepare as if it could be me. It's not.
"I'm never going to have 15,000, 20,000 people cheering for me, chanting USA, screaming my name, that kind of stuff.
"I'm lucky enough to have had that for 14 years. I try to look at the positives. Most people never have had that. Most people in the world will never be able to relate to that.
"I'm looking forward to a new stage in my life. I'll miss this one. I could have finished this year a little better, this tournament, but to expect to win more matches in my mind would just be greedy."
Former champion Lleyton Hewitt saw off American Brian Baker 6-3 4-6 6-3 6-4 to set up a showdown with del Potro, while ninth seed Stanislas Wawrinka beat Radek Stepanek in straight sets.
Roger Federer and Rafael Nadal both play their second-round matches on Thursday, with Federer taking on Argentina's Carlos Berlocq while Nadal plays Rogerio Dutra Silva of Brazil in the night session.