Roger Federer conceded he was not in good enough shape to challenge for another Grand Slam title as the elusive US Open clash with Rafael Nadal slipped away again.
After the Spaniard defeated Andrey Rublev, it seemed virtually nailed on that New York would witness a first meeting between the great beasts of men's tennis in the semi-finals, but then Juan Martin del Potro upset the applecart with a four sets victory - 7-5 3-6 7-6 (10-8) 6-4 - over Federer.
The 36-year-old insisted it was his physical struggles, along with the form of Del Potro, that decided the match.
Asked if he was thinking about Nadal, the third seed said: "I wasn't. You were. It's not more frustrating. It's been a tough tournament throughout.
"I honestly was only thinking about tonight. My head didn't even wander during the match. I knew it was going to be a tough one. I had struggled too much throughout the tournament to think too far ahead.
"I'm not disappointed because it's been a good run this year already. Unfortunately I ran into a guy who was better than me.
"Juan Martin deserves it more. The way I played or am playing right now, it's not good enough to win this tournament. It's better I'm out and somebody else gets a chance."
Del Potro, who has struggled with injury in recent years, said: "I think I played my best match of the tournament."