Andre Agassi v Juan Carlos Ferrero
Agassi continues to defy the odds as he targets a sixth US Open final and a third title at Flushing Meadows.
AGASSI (1) v FERRERO (3)
At 33, he is the oldest player in the draw and could become the oldest men's champion since 1970 - but he will have to overcome a player 10 years his junior to achieve that feat.
His route to the last four has been highly impressive, dropping only one set against Taylor Dent in the fourth round.
He was expected to face a battle against Guillermo Coria in the quarter-finals but though the Argentine, who beat Agassi at the French Open, was struggling with an injury, the American had to be at his clinical best to come through in straight sets.
It means Agassi is yet to play more than three sets in a match, and that could be crucial in the daunting schedule of a possible three matches in three days the men are now facing.
Ferrero, in contrast, needed five sets to down the veteran Todd Martin and overcame Lleyton Hewitt in four in the last eight.
However, the French Open champion is fast proving that he is not just a claycourt specialist and he has the psychological advantage of a 2-1 lead in head-to-heads with Agassi.
One of those victories came on the hard courts of Shanghai last year at the Tennis Masters Cup, before Ferrero narrowly lost out to Lleyton Hewitt in the final.
While Agassi is a firm favourite among American fans, Ferrero has hardly merited a mention on his route on the semis but the Spaniard will make waves if he can overcome Agassi, a win which would see him become world number one.
Andy Roddick v David Nalbandian
Such has been Roddick's stunning form before and during this year's US Open that it will be a major surprise if he does not win the title.
RODDICK (4) v NALBANDIAN (13)
The American, who turned 21 a week ago, won back-to-back Masters Series titles in the lead-up to the final Grand Slam of the year and took the lead in the ATP Champions Race, which rates the form players of the season.
He has lost only two matches since linking up with coach Brad Gilbert after a disappointing first-round exit at the French Open.
Gilbert has worked with Roddick on biding his time before utilising his explosive forehand to finish off points and his backhand, so often a weakness, has become a much more potent weapon.
In Nalbandian, he faces a player he has never lost to before but the Argentine is in the form of his life after consecutive wins over Mark Philippoussis, Roger Federer and Younes El Aynaoui in New York.
American fans are dreaming of a Roddick-Agassi final but Nalbandian, a former Wimbledon finalist, is just the sort of player who could upset the young American's rhythm with his dogged baseline play.