The 24-year-old became the first American man to reach the semi-finals of the singles at Flushing Meadows since Andy Roddick 16 years ago when he followed up his huge upset of Rafael Nadal by beating Andrey Rublev.
Now Tiafoe has another Roddick achievement in his sights as he bids to become the first American man to win a slam crown since the 2003 US Open.
It would complete a remarkable journey from beginnings that were both unpromising and serendipitous.
Tiafoe’s parents were immigrants from Sierra Leone looking to make their way and a better life for their twin boys in the United States.
Constant Tiafoe took a labouring job building a tennis centre in Maryland, which led to him becoming caretaker when it opened. With Frances and Franklin’s mother working night shifts as a nurse, they lived with their father in a spare room at the centre, sleeping on a massage table.
The family could not afford lessons or equipment but Constant was a valued member of staff and the boys began playing for free. Frances quickly became absorbed in the game and coach Misha Kouznetsov spotted his talent, setting him on the path to the professional game.
Now Tiafoe is carrying the hopes of his country and soaking up the adulation of the thousands of fans who cheered him on to victory in Arthur Ashe Stadium.
“That stuff gets me emotional, for sure,” he said. “Seeing people screaming your name, just loving what you’re doing. That’s awesome. That’s what it’s all about. Everyone loves a Cinderella story. I’m just trying to make one.
“Every time I win, I just want to inspire a bunch of people to just know that anything is possible. For me do this and talk about how I feel about being in the US Open from my come-up is crazy.
“At the end of the day, I love that because of Frances Tiafoe there are a lot of people of colour playing tennis. That’s obviously a goal for me. That’s why I’m out here trying pretty hard.”
Tiafoe made a strong transition to the senior game, reaching the quarter-finals at the Australian Open in 2019, which he admits led to complacency.
“You go through different stages of your life,” he said. “When I came on the scene, flying up the rankings, everything was kind of good. I got a bit complacent in 2019. It took me a long time to just get myself together.
“During that time the cameras weren’t on me. I was able to just get better and do my own thing. I stopped trying to be the guy. When things were going to happen, it was going to happen.”
A key development in Tiafoe’s improvement was his hiring in 2020 of former top-10 player Wayne Ferreira as coach.
“I think I helped him because I played and I went through the issues of being relatively talented and being lazy, and then finding the right team, people behind me pushing me to do the right thing day to day with the food, practising and with the fitness and gym work,” said Ferreira.
“That’s something he had to really change. His food intake was terrible at the beginning. The effort in the practices and on the court wasn’t good enough.”
Ferreira is equally inspired by Tiafoe’s path to the top, saying: “I think it’s a great message for anybody really that you can end up achieving greatness from where you are coming.
“Frances has been lucky in some ways of having great help from people along the way. But it’s a great story. Hopefully there will be a movie about it one day.
“But he has to win the grand slam first. You only get movies if you do well.”
Tiafoe will take on Carlos Alcaraz after his late-night epic against Jannik Sinner, while Casper Ruud meets Karen Khachanov in an unexpected last-four line-up. Of the quartet, Ruud is the only one who has previously made a grand slam final having finished runner-up at the French Open this year.
“Everyone is going to be in those first-time situations,” said Tiafoe. “People might gag under pressure. People may lift up.
“To have those guys, that was always a problem. Didn’t really matter where you’re from, what was your name. You ran into those guys, and they just said, ‘See ya’.”