Argentina's Juan Martin del Potro beat Federer in the US Open quaterfinals Photograph: (Reuters)
Juan Martin del Potro beat Roger Federer 7-5 3-6 7-6(8) 6-4
"The best player won today, by far, and I don't have a problem with that," Federer said after the match.
Federer felt he was slightly unprepared due to injury which he had suffered before the US Open.
"I don't want to take anything from Juan Martin but when you get injured before a tournament, you are not focused on training or on how to play during the tournament," the former World No-1 said.
"It was a bit the case for me before the US Open. Then I had to play a couple of five setters and you start to hurt a little bit everywhere," he added.
Fans and experts were, of course, looking forward to a Nadal-Federer clash with ticket prices for the match skyrocketing.
"I didn't even think about it, as I lost that match, that it's not going to happen," Federer said referring to a semi-final matchup with Nadal which was spoiled by a resurgent del Potro.
"Of course it is a pity but, you know, Juan Martin deserves it more. I feel I have no place in the semis and he will have a better chance to beat Rafa, to be honest," Federer said.
del Porto who surprised everyone with his all court, power display told reporters after the match he was ready for Nadal.
"I played (Nadal) in 2009 too, the same as Roger and hopefully I can repeat the result," he said.
"We look older but he's having an amazing season, number one in the world but with this amazing support anything can happen," the Argentian added.