It's often said that Roger Federer doesn't sweat during a tennis match. The all-time great barely broke one in his easy second round win at the US Open. But he's certainly aware of the high number of player retirements due to the extreme heat this week in New York.

His response? There's no excuse.

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After easily defeating Belgium's Steve Darcis in just over an hour on Thursday night, Federer was asked about the 14 player retirements this week, the bulk of them heat-related.

"I'm surprised to hear that players are retiring because of heat. I mean, if you're injured, it's different and all that. But I'm sure from the 12 or 13 players that have retired, I'm sure there's involvement with heat.

What I don't understand, if that's the case, we've been here in North America for some time. It's not like, all of a sudden, hot. I mean, it was more on the warmer side, but it's not like impossible, to be quite honest. Really no excuse for that."

The record number of retirements, including that of American Jack Sock, started a debate of whether the ATP should a create similar heat-rule, like the WTA has for its players, or if best-of-five matches at the majors should be discontinued.

"I think everybody should be well-prepared," Federer added. "I know we don't play many best-of-five-set matches all the time, so of course the body can react funny once you exceed the two-and-a-half to three-and-a-half hours of play. Mardy Fish, that's an exception. He's not been that well-prepared because he hasn't had the matches in his body.

Other players, I don't know where they come from. So there are exceptions to those players. Maybe some guys already came in too tired, whatever it was.

I think you have to analyze case by case. But I think other players should be so fit that heat really shouldn't matter at that point, the ones we've been playing in."

Federer will next face Germany's Philip Kohlschreiber in the next round.

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