The 24-year-old simply stood there soaking up the atmosphere created by a raucous Arthur Ashe Stadium.
It felt like a seminal moment in the American’s career; a culmination of hard work and raw talent which has long been heralded as the potential future of men’s tennis in the country.
Expectations of Tiafoe have been high for a long time and the world No.26 is now looking more than comfortable on the sport’s biggest stage.
Should Tiafoe reach the semifinals by beating Andrey Rublev on Wednesday, he would record the best grand slam result of his career and the achievement will be made all the more impressive given his humble beginnings.
Tiafoe’s route into tennis, after all, was in no way traditional.
Their father, Constant Tiafoe, started working at the Junior Tennis Champions Center in Washington, DC back in 1999 and eventually moved into one of its vacant storage rooms while working around the clock.
His two boys would sometimes stay with him, sleeping on a massage table, while their mother worked night shifts as a nurse.
The unusual gateway into the sport gave Tiafoe an opportunity to start developing his skills and, after beginning to train at the facility, he didn’t look back.
Driven by the work ethic of his parents, he won the prestigious Orange Bowl — one of tennis’ most prized junior tournaments — at 15, becoming the youngest boys’ singles champion in the tournament’s history.
He joined a list of previous champions which included Roger Federer, Andy Roddick, Ivan Lendl, Jim Courier, John McEnroe and Bjorn Borg.
It was a sign of things to come.
Maturing on tour
Tiafoe turned professional in 2015 and started getting familiar with the rigors of the senior tour.
He broke into the world’s top 100 and began to assert himself at grand slams — reaching his first quarterfinal at the Australian Open in 2019 before losing to Nadal.
Three years on and he finds himself at another quarterfinal, only this time he feels more ready to grasp the opportunity.
“Honestly, when I first came on the scene, I wasn’t ready for it mentally and mature enough,” he said on court after beating Nadal. “I’ve been able to develop and I have a great team around me.
“I’m happy I won in front of my mom, my dad, my girlfriend and my team and to have them see what I did.”
While he cements himself as a contender on the court, Tiafoe is also pursuing social justice off it.
In 2022, he told CNN Sport that the lack of diversity in the sport had made him feel like an “outsider,” and he vowed to continue fighting for equality while he still had the platform to do so.
He created a protest video in 2022 to raise awareness of racial injustices after the death of George Floyd sparked protests across the world.
In collaboration with a host of Black players and coaches — such as Serena Williams and Coco Gauff — he posted the “Racquets down, hands up” video to his social media channels.
On the court, his next match against Rublev will certainly be the biggest of his career to date.
The home crowd will be hoping its hero can keep hitting new heights in his bid to win a maiden grand slam title.
His performances have even attracted the attention of some of the biggest names in sport, with NBA star LeBron James congratulating Tiafoe on making the quarterfinals.
Make no mistake, though, this is no overnight success story. It’s a product of thousands of hours of work and a mentality that won’t take no for an answer.
However, while the weight of a nation rests on his shoulders, Tiafoe has always just focused on making his parents proud.
“With them trying so hard, I felt like I didn’t want to let them down,” he told CNN Sport in 2015. “I felt like I didn’t want to let the opportunities go for granted.”
CNN’s Will Edmonds and Christina Macfarlane contributed reporting.