Eddie Hearn, promoter for IBF, IBO, WBA, WBO heavyweight champion Anthony Joshua, expects a very tough fight when his man collides in the ring with undefeated contender Jarrell Miller.
A deal is nearly complete for Miller to challenge Joshua on June 1 at Madison Square Garden in New York City.
The bout would see Joshua, who's exclusively fought in the UK, make his debut in the American market.
Hearn believes the fight will further build a mega-fight unification with WBC world champion Deontay Wilder.
The contest with Wilder was being discussed last year, but their negotiations fell through.
Wilder instead faced Tyson Fury - and they fought to a controversial twelve round split draw in December at Staples Center in Los Angeles.
The two big heavyweights are now going to collide in a rematch in the coming months.
But in order for Joshua to face the winner, he must go through Miller to make that happen.
"It is looking like Jarrell Miller,” Hearn said to Boxing News.
"Miller is hardly a household name, not in America and certainly not in Britain. But the money on offer for Joshua to fight him will still be massive. If we can’t deliver the fight that we want to deliver here [in the UK], it’s a great to go and break the US market. I think what he’ll do over there will be incredible.
"I think he’ll be huge over there and I think it will build a potential fight, if Wilder wins, makes that fight even bigger and we know how big [Tyson] Fury [against] Joshua is here anyway. I just think it’s a great move for him and I think it’s a tough fight, I really do. Over there new experience, new ring, new canvas, new commission, all this kind of stuff. It’s not going to be easy."