As a youngster, Frances Tiafoe, the son of a Sierra Leone immigrant, played tennis in hand-me-down gear and dreamed of the day he'd face Roger Federer at the US Open.

On Tuesday, that wish, forged from hours of hitting a ball against the wall of a Maryland club where his father worked as a maintenance man, comes true in front of almost 25,000 fans on New York's showpiece Arthue Ashe Stadium.

It's a long way from the days when cash-strapped Tiafoe practiced with his twin brother Franklin at the College Park Tennis Club.

"I played with hand-me-down rackets and gear from my wealthier peers, or used demo rackets the club supplied," 19-year-old Tiafoe told theplayerstribune.com.

"While my dad worked, I picked up the game during nights and weekends at the facility when the other kids weren't around.

"I'd hit against the wall by myself, mimicking techniques I had seen older boys at the academy do. I'd imagine I was playing against Rafa or Roger in the US Open, that those guys were just on the other side of the wall."

Tiafoe was just six months old when Federer was winning the Wimbledon junior title, the Swiss star's first step on the road to turning pro later that year.

Now ranked at 70 in the world, Tiafoe has already illustrated why he's being talked of as America's most likely next Grand Slam champion.

At Cincinnati, in the run-up to the US Open, he defeated world number six Alexander Zverev, just weeks after losing to the German in the Wimbledon second round.

He has also already faced Federer, losing in two tight sets at Miami in March this year where "the ground shook," the American teenager remembered.

"What are the chances that a kid like me, a kid with immigrant parents who picked up the game the way I did, who came up how I came up, would ever get the chance even to lay eyes on Roger Federer?"

Federer, the 19-time major winner who is chasing a record sixth US Open title, said he was grateful that he had already got a look at Tiafoe in Miami.

"Clearly he has nothing to lose but everything to gain," said the 36-year-old.

A defeat for reigning Australian Open and Wimbledon champion Federer on Tuesday under the Arthur Ashe lights would be a shock of seismic proportions.

He has never lost in the first round in New York. His earliest exit came on his debut in 2000, back when Tiafoe was still to reach his second birthday.

"He's an aggressive baseliner like so many of the Americans," said Federer, who missed the 2016 tournament through injury.

"Thankfully I played him in Miami this year so I have a little bit of an idea of how he plays, and his patterns and what he prefers to do.

"I'm excited to play on center court for the first time with the proper structure and roof now. I missed it last year. I'm very excited."

Source: AFP