Roger Federer dropped the first set he played at this year's U.S. 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 for 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, too.

"Maybe it's not a bad thing to go through a match like this," said Federer, who has now won his past 62 first-round Slam matches. "It was very similar at Wimbledon."

That's true. He ceded his very first set at the All England Club in July, then wound up making it all the way 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."