NEW YORK -- Roger Federer dropped the first set he played at this year's US Open -- against someone named Nagal.
No, not Nadal.
Nagal.
Federer shrugged off that slow start and came back for a 4-6, 6-1, 6-2, 6-4 victory Monday night against Sumit Nagal, a qualifier from India ranked 190th.
How did the 20-time Grand Slam champion deal with digging himself that hole?
"Just try to forget it,'' Federer said during his on-court interview in Arthur Ashe Stadium. "Play tough. Stay with him. It was a tough first set for me. ... Credit to him.''
When that first set ended, there were plenty of people looking on in disbelief -- in Federer's guest box, certainly; around the stands, of course; and in front of TVs at home, surely.
"People expect a different result,'' Federer said. "I expect something else.''
This was not, after all, Rafael Nadal, someone Federer has never faced at Flushing Meadows but trails 24-16 head-to-head overall.
Instead, it was Nagal, who is now 0-5 in tour-level matches in his career, trailing Federer by 1,224 victories.
"It would have been a better story,'' said Nagal, who now heads to Genoa, Italy, to enter a low-tier Challenge Tour event on red clay, "if I had got another set or more.''
Federer was a big part of what transpired in the early going: Of the 32 points Nagal won in the first set, only three arrived via his own winners. Of the other 29, 19 were thanks to unforced errors by Federer, and another 10 were forced errors off the Swiss star's racket.
One particular issue was Federer's serve: He won merely seven of his initial 20 second-serve points.
But he returned well throughout, breaking in Nagal's first service game of every set, and eventually, the rest of Federer's game came around.
"Maybe it's not a bad thing to go through a match like this,'' said Federer, who has won his past 62 first-round Slam matches. "It was very similar at Wimbledon.''
Federer ceded his first set at the All England Club in July, then wound up making it to the final -- even holding championship points before eventually losing to Novak Djokovic in a fifth-set tiebreaker.
Nagal soon saw a better Federer than was present at the outset Monday.
"He loves putting pressure on the other guy. The thing with him is you don't know what type of shot [he'll play],'' Nagal said. "He's always making you think. ... You have no idea where the ball is coming back.''
Earlier in the day, defending champion and top seed Novak Djokovic won his opening match 6-4, 6-1, 6-4 against Roberto Carballes Baena of Spain.
It was Djokovic's 54th consecutive first-round victory at a Grand Slam. The last time he lost in the opening round of a major was the 2006 Australian Open against Paul Goldstein.
With Monday's win, Djokovic is 57-2 overall in the first round of majors, giving him the best win percentage by any man in the Open Era.
Djokovic gave an on-court interview in which he acknowledged dancing in Central Park as part of his prematch preparation. He promptly went to his bag and pulled out two rackets that he used as faux maracas while he showed off his Latin dance moves to the Arthur Ashe Stadium crowd.
Djokovic, winner of this year's Australian Open and Wimbledon crowns, is seeking his fourth US Open and 17th Grand Slam tournament title.
It was part of a full slate of men's matches as the year's last Slam began in New York. Earlier in the day, Jenson Brooksby, an 18-year-old Californian, upset Tomas Berdych 6-1, 2-6, 6-4, 6-4 for his first career Grand Slam win and said afterward that he might reconsider his plans to play at Baylor University after the US Open.
Players are guaranteed $100,000 for reaching the second round of singles play at the US Open, but Brooksby would have to give up his amateur future if he takes it. That makes his decision even more difficult.
"Yeah, it's definitely financial because, like, I would get four years of free college if I went just for one semester, compared to just the money I earn here,'' Brooksby said. "So got to figure that all out.''
It was his second straight year playing in the tournament, after he received a wild card last year. This time, he made it through qualifying and took advantage of a clearly limited Berdych, who has battled injuries for much of this season.
"That's very frustrating. When you do the whole preparation, everything's fine, goes well, and then you get on court, and basically there's no way I can compete with the guys in this shape,'' Berdych said.
Brooksby wasn't the only young American to win Monday, as Reilly Opelka, who turns 22 on Wednesday, knocked off 11th-seeded Fabio Fognini of Italy.
The 6-foot-11 Opelka hit 26 aces in his 6-3, 6-4, 6-7 (6), 6-3 victory.
Currently ranked a career-high No. 42, Opelka acknowledged that his serve wasn't at its very best but said the victory "shows that I've got more than that to back it up."
An even younger American than Opelka or Brooksby came oh-so-close to pulling off another surprise later Monday, but 16-year-old Zachary Svajda of California couldn't quite hold on after building a two-set lead against 37-year-old Paolo Lorenzi of Italy, eventually succumbing 3-6, 6-7 (5), 6-4, 7-6 (4), 6-2.
The age gap of 21 years was the largest between male opponents at a Grand Slam tournament since 1978.
Svajda, who earned his berth in New York by winning the U.S. 18s national championship, was the youngest man in the main draw at Flushing Meadows since Donald Young also was 16 in 2005.
Kei Nishikori, meanwhile, advanced to the second round when qualifier Marco Trungelliti had to retire with the 2014 US Open runner-up leading 6-1, 4-1. Nishikori is the No. 7 seed this year after reaching the semifinals in Flushing Meadows last year.
The Associated Press contributed to this report.