NEW YORK: Frances Tiafoe and Taylor Fritz battle for the honour of delivering the United States' first male Grand Slam finalist in 15 years on Friday as Jannik Sinner and Jack Draper also break new ground.
The four have fought their way through in a tournament which saw shock first-week departures for favourites Novak Djokovic and Carlos Alcaraz.
As a result, a first-time US Open champion will be crowned on Sunday.
It also means that for the first time since 2002, none of the four Slams will have fallen to the 'Big Three' of the long-retired Roger Federer, Rafael Nadal or Djokovic.
AFP Sport looks at the two semi-finals (x denotes seed; 1900 GMT start):
Head-to-head: Draper leads 1-0
– Australian Open champion Sinner is playing in his maiden US Open semi-final while close friend Draper is in the last-four of any Slam for the first time.
Italian top seed Sinner, who arrived in New York plagued by controversy over two failed drugs tests, has seen title rivals four-time champion Djokovic and 2022 winner Alcaraz eliminated.
Also out early was former runner-up Alexander Zverev in a tournament of so many upsets that the 23-year-old Sinner is the only member of the top 10 to have reached the semi-finals.
Victory on Friday would make him the first Italian man to reach the US Open final.
To get there, he needs to put his friendship with 22-year-old Draper to one side, just weeks after they played doubles together in Montreal.
"We text each other when we have good or bad times," said Sinner.
"It's a great friendship. Obviously we try to put this away for the hours we are on court but whenever we shake hands, it's again friendship and all is good."
Left-handed Draper has blitzed his way through the draw and is the only one of the four semi-finalists not to have dropped a set, winning 60 of his 63 service games.
Draper, who models when he is not playing tennis, is the first British man to get to the semi-finals since Andy Murray won the 2012 title.
The Briton defeated Sinner in their only previous meeting, but that win on grass at Queen's came three years ago.
"We send each other messages in good moments, bad moments. It's a tough sport to play when you're a young guy," said Draper in praise of his friend.
"You're on the road, you're playing such a relentlessly intense sport, both physically, emotionally, and it's difficult, we haven't got many friends."
Head-to-head: Fritz leads 6-1
– It's been 21 years since Andy Roddick captured the US Open and that was the last time an American man lifted a Grand Slam trophy. Fritz and Tiafoe where just five years old at the time.
Roddick was also the last US man to reach a Grand Slam final when he lost to Roger Federer at Wimbledon in 2009 and the last to go all the way to the US Open title match. That was 2006 and again he lost, again to Federer.
"Taylor and I had a conversation about being the number one, number two Americans for a very long time," said Tiafoe ahead of the first all-American Grand Slam semi-final since Andre Agassi defeated Robby Ginepri at New York in 2005.
"I remember we were sitting on a plane some years ago, and he's a pretty to-himself kind of dude, and he's, like, 'Bro, I think me and you are going to be one, two Americans and leading the way."
Fritz had lost four Grand Slam quarter-finals before ending that run when he knocked out fourth-ranked Alexander Zverev.
Tiafoe is in the semi-finals for a second time in his last three appearances.
Fritz enjoys a 6-1 head-to-head lead over his friend but Tiafoe has dismissed that as irrelevant ahead of Friday night's clash under the Arthur Ashe Stadium lights.
"It's different on Ashe, man," said Tiafoe. --AFP