World No 1 and defending champion Rafael Nadal will put his weary body on the line against the brutal power of Juan Martin del Potro on Friday with a place in the US Open final at stake.
Nadal, the three-time champion, faces 2009 winner Del Potro and is two wins from clinching an 18th Grand Slam title.
With an 11-5 career head-to-head advantage over the giant Argentine, the Spanish superstar comes in a as favourite, but this has been an unpredictable US Open with Federer knocked out by Australian world number 55 John Millman in the fourth round and Nadal coming close to joining his greatest rival at the exit door after a scare against Dominic Thiem.
Whoever gets through Friday will have yet another major challenge on their hands in Sunday’s final where either Novak Djokovic or Kei Nishikori will await.
Meanwhile, two-time US Open champion Djokovic will be playing in his 11th consecutive semifinal in New York, just two months after defying the odds to lift a 13th major at Wimbledon.
The 31-year-old Serb holds a 14-2 advantage over Nishikori including wins at Wimbledon and Rome this year.
But one of Nishikori’s wins came in the semifinals in New York in 2014 when the Japanese star finished runner-up to Marin Cilic.
“When Kei is on, he’s a top-five, top-10 player,” said Djokovic.
“He has a great two-handed backhand, great footwork and is one of the quickest players on tour.”
Nishikori, part of a history-making double act with Naomi Osaka in New York as the first Japanese man and woman to make the semifinals of the same Slam, missed the 2017 US Open with a wrist injury.
“2014 will always be a good memory here. It was a tough battle and it will give me good confidence, even though I don’t remember a lot of it,” said the 28-year-old after getting revenge on Cilic in the quarterfinals.