Juan Martin del Potro has remained on course to win a second US Open title by beating Roger Federer 7-5, 3-6, 7-6 (10-8), 6-4 in the quarter-finals at Flushing Meadows.
With Rafael Nadal securing an emphatic 6-1, 6-2, 6-2 win earlier in the day against Russian teenager Andrey Rublev, all seemed set for two of the sport's greatest ever players to meet in the US Open for the first time for a place in the final.
However, del Potro had other ideas. Having defied illness to come back from two sets to love down in a sensational fourth-round win over Dominic Thiem - a performance that led to him being described as "del THORtro" on Twitter by Federer - the Argentinean backed that up with another fine display to send the Australian Open and Wimbledon champion crashing out.
The match was a repeat of the 2009 final at Flushing Meadows, when del Potro won his only Grand Slam to date. Indeed, since then he has yet to reach a Grand Slam final as his career has been blighted by a series of wrist injuries.
However, del Potro's run to the Olympic final last year showed the talent has not been diminished and, at the age of 28, he may now be in just the right place to take advantage of age and injury among the stars who have dominated in recent years.
Federer has been feeling the effects of both recently, with the 26-year struggling through the early rounds with a sore back. He appeared to be back to his best and fittest in his fourth-round straight-sets win against Philipp Kohlschreiber, but admitted afterwards that he was always feeling vulnerable.
He remarked: "It was one of those matches where if I ran into a good guy I was going to lose, I felt.
"I don't want to say I was in a negative mindset, but I knew going in that I'm not in a safe place. It might have depended too much on my opponent - and I don't like that feeling.
"I had it throughout the tournament, and I just felt that way every single match I went into."
For del Potro, the opposite was true. He remarked: "I don't know what the turning point was, maybe I got lucky. I can't believe I am back after all my injuries and surgeries."
Nadal's imperious form against Rublev suggests he will still be the favourite against the only other Grand Slam winner left in the draw, but fans booking corporate hospitality for the ATP World Tour Finals at the O2 in November can look forward to seeing Del Potro in action.
The winner of Nadal against del Potro will face either Pablo Carrena Busta or Kevin Anderson, either of whom will be playing his first Grand Slam final.
Anderson reached the semi-final at the expense of Sam Querrey, but while the New York crowd no longer have an American to cheer in the men's tournament, they are now guaranteed to see one win the women's singles.
The semi-final line-up will feature the favourite Venus Williams against Sloane Stephens, while Coco Vandeweghe will take on Madison Keys. It is the first all-American semi-final line-up in the women's singles at Flushing Meadows since 1981.
Image: Getty, from Keith Prowse subscription