Roger Federer does not have "the crystal ball" to see how many more chances he will have to add to his grand slam tally after missing a major opportunity at the US Open.
With Novak Djokovic having exited in the fourth round, Federer looked to have a clear path through to a potential blockbuster final with Rafael Nadal.
However, he fell victim to an incredible fightback from Grigor Dimitrov in Tuesday's quarter-final, the world number 78 coming from two sets to one down to prevail in three hours and 12 minutes.
The defeat was marked by a back problem that saw Federer leave the court for treatment in the fourth set.
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He returned for the fifth but never looked capable of stopping Dimitrov from marching into his third slam semi-final.
Federer has demonstrated remarkable longevity to still be competing for majors at 38 years of age. However, he conceded he let a chance go begging at Flushing Meadows this year.
"I'm disappointed it's over because I did feel like I was actually playing really well after a couple of rocky starts," Federer told a media conference.
"It's just a missed opportunity to some extent that you're in the lead, you can get through, you have two days off after. It was looking good.
Class and Grace.
— US Open Tennis (@usopen) September 4, 2019
@rogerfederer | #USOpen pic.twitter.com/JnyfRkmlF9
"But [I've] got to take the losses. They're part of the game. Looking forward to family time and all that stuff, so... Life's all right."
Asked if he will have more opportunities to win majors, he replied: "I don't have the crystal ball. Do you?
"I hope so, of course. I think still it's been a positive season. Disappointing now, but I'll get back up, I'll be all right."