Roger Federer dismissed the suggestion that his mystery injury was to blame for his shock US Open quarter-final defeat to Grigor Dimitrov.
The 38-year-old twice led the unseeded Bulgarian before appearing to struggle throughout the fourth set, making a series of unforced errors.
The 20-time Grand Slam winner called for the trainer onto the court just after Dimitrov had forced a deciding set and headed to the locker room for treatment.
Federer never looked up to the task in the final set, with Dimitrov going up a double break before clinching victory in three hours and 12 minutes.
In his post-match press conference, Federer revealed he had been struggling with a back and neck problem prior to the match, but refused to make excuses for his defeat.
"I just needed some treatment on my upper - what is it - back, neck. Just needed to try to loosen it up, crack it and see if it was going to be better," Federer told reporters.
"This is Grigor's moment and not my body's moment, so it's OK.
"[I] had a little bit [of pain] this afternoon. That's it. I was able to play. It's OK, it's how it goes. I tried my best.
"It was not too bad to give up or anything. Grigor was able to put me away and I fought with what I had. That's it."
Federer, who hasn't won a Grand Slam since the Australian Open in 2018, missed his chance for a potential reunion with Rafael Nadal in the final.
Instead, Dimitrov will play Russian fifth seed Daniil Medvedev in the semi-final, while Nadal faces Diego Schwartzman in his quarter-final match on Wednesday.
