He is scheduled to play 19-year-old Bernard Tomic of Australia in the second round Friday night at Arthur Ashe Stadium.
Roddick's impending departure was by far the biggest news of Day 4 at the year's last major tournament, overshadowing some otherwise noteworthy on-court developments in the afternoon.
There was the loss by fifth-seeded Jo-Wilfried Tsonga, the 2008 Australian Open runner-up, against a man ranked 52nd.
And there was a spate of victories by American men, two who are Roddick's contemporaries and good pals (32-year-old James Blake and 30-year-old Mardy Fish), and two who have been viewed as possible successors as the best the country has to offer in the sport (19-year-old Jack Sock and 24-year-old Sam Querrey).
"I saw the press conference just before I came out here. I had a feeling, thought it might be, because he's someone who puts heart and soul into every match. It gets tougher as you get older, and I don't think he could keep doing it the same way," said the 115th-ranked Blake, whose 6-1, 6-4, 6-2 upset of No. 24 Marcel Granollers of Spain was stunning for its ease.
No. 23-seeded Fish came back to beat two-time U.S. Open semifinalist Nikolay Davydenko 4-6, 6-7 (4), 6-2, 6-1, 6-2, the tournament-record 10th match in which a man erased a two-set deficit and came all the way back to win.
Men should be playing best-of-three-set matches at Grand Slam tournaments, the way women do.
"Why (do) girls play best of three sets and we should play best of five sets and have the same prize money?" Davydenko said, reviving a familiar debate.
"Why are we playing five-set matches? We need to play best of three in Grand Slams. Everybody will support (that idea, even Roger) Federer. For Federer, it's easy to win in one hour, two sets. No need to run (for) a third set," Davydenko said.
Of course, for Federer, winning three sets before his opponent does never has been much of a problem, and the 17-time major champion moved into the third round with a routine 6-2, 6-3, 6-2 victory over 83rd-ranked Bjorn Phau of Germany on Thursday night.
Naturally, he was asked about Roddick, a guy Federer beat in all four Grand Slam finals they played against each other, including one at the U.S. Open and three at Wimbledon.
"Oh, man. He's a great man," Federer said. "I've had some great battles with him for a long, long time. Obviously, the Wimbledon finals come to mind, the ones we played together. He's a great, great competitor and a great champion, really."
Looking ahead to Friday, Federer also mentioned that he thinks Roddick "truly deserves a great ovation, a great atmosphere, a great crowd. ... I'm definitely going to watch it. It's not one to miss, and I hope it's not his last."
Querrey also echoed the sentiments of plenty of others about Roddick's decision.
"He's been my biggest role model the last 10 years, playing tennis, watching tennis. He's been a really great guy, a great leader to us all. Nice and kind. Really generous to the up-and-comers," Querrey said after beating Ruben Ramirez Hidalgo of Spain 6-3, 6-4, 6-3 to reach the third round. "For me, for ... the 18-year-olds now, he's just been an unbelievable champion, a Hall of Famer."
While few seemed to have an inkling that Roddick would say farewell during these two weeks, 14-time major champion Serena Williams, for one, was not taken aback.
Indeed, after beating Maria Jose Martinez Sanchez of Spain 6-2, 6-4, Williams said she knew this was coming.
"I mean, he told me a while ago last year that this would be it," she said. "We were talking about it. I was just thinking, 'Change your mind, Andy. Change your mind.' But I guess he didn't."
His title in New York nine years ago was the last time an American man won a Grand Slam singles title, and Roddick reminisced as he often has in the past about coming to the U.S. Open with his parents as a present when he turned 8 years old.
Buoyed by a booming serve he used to hold the record of 155 mph and big forehand, Roddick is 610-212 (a .742 winning percentage) with 32 titles, including two this year at Atlanta and Eastbourne, England. He also helped the United States end a 12-year David Cup drought by winning the 2007 title.
"Look, he's been our best player for many, many years. Do we love to have a guy like that out there? Sure. Was it great that he's American? Sure," U.S. Tennis Association CEO Gordon Smith said. "We could use another dozen Andy Roddicks, and we're grateful for all he's meant to American tennis, to the Davis Cup, to the U.S. Open."
Roddick's announcement came one day after four-time major champion Kim Clijsters played the last singles match of her career, a second-round loss to Laura Robson.
"I haven't done this before. I'm sure it'll be very emotional. I'm sure I'll still be nervous," Roddick said, looking ahead to facing Tomic. "I don't know."
Roddick has been dealing with a series of injuries over the past few seasons, and in February dropped out of the top 20, then slid to No. 34 in March, his lowest ranking since 2001.
A hurt right hamstring forced Roddick to retire during his second-round match at the Australian Open in January, and he lost in the first round at the French Open and third round at Wimbledon.
"With the way my body feels, with the way that I'm able to feel like I'm able to compete now, I don't know that it's good enough," Roddick explained. "I don't know that I've ever been someone who's interested in 'existing' on tour."
A closer look at Roddick's career
Age • 30
Born • Omaha, Neb.
Career record • 607-209
Career titles • 32
Grand Slam record • 128-44
Notable finishes • 2003 U.S. Open champion, three-time Wimbledon runner-up (2004, 2005, 2009)
Career earnings • $20.5 million
Note • Record, titles and earnings do not reflect 2012 U.S. Open
P Men's second round and women's third round
Friday, 11 a.m. and 5 p.m.
TV • ESPN2