Men's quarter-finals - day 12
Andy Roddick was in ruthless form in a straight sets win over Sjeng Schalken which ensured his first ever appearance in a US Open semi-final.
The American fourth seed will now face David Nalbandian, who defeated Younes El Aynaoui in a thrilling encounter.
Andre Agassi and Juan Carlos Ferrero meet in the other semi.
"I've lost a couple of quarter-final matches, so I'm pleased," said Roddick.
"But, you know, hopefully it's not over yet."
Roddick will be a strong favourite to reach his first major final, after a scintillating display against Schalken.
Schalken, the 12th seed, is respected as one of the more consistent players on the tour but he never came close to troubling the in-form 21-year-old.
Even one unexpected blip, when Schalken unexpectedly broke serve to trail 5-4 in the first set, was quickly corrected as Roddick immediately broke again to take the set.
Roddick's 17th consecutive win took just one hour 25 minutes.
Nalbandian, meanwhile, needed nearly four hours to quell the challenge of the effervescent El Aynaoui in the pick of the men's quarter-finals.
The Argentine, who upset Wimbledon champion Roger Federer in the previous round, looked on course for a routine win when he grabbed the first set on a tie-break and cruised through the second.
Nalbandian is the first Argentine in the US Open semis since 1977
El Aynaoui, bidding to reach his first ever Grand Slam semi-final, had treatment on a knee injury midway through the second set but fought back brilliantly to take the third set.
And it was Nalbandian who wavered in the fourth as the Moroccan went up a break, but the Argentine rediscovered his focus to recover the break before sealing a 7-6 (7-2) 6-2 3-6 7-5 victory.
"I'm not tired," Nalbandian insisted afterwards. "I'm going to be ready. It's going to be tough, the crowd is going to be for Roddick, but I don't care. I'm ready to fight."