Heavyweight boxing champion Anthony Joshua will defend his WBA, IBF and WBO titles against Andy Ruiz on June 2 (NZ time) at Madison Square Garden in New York.
Joshua was left in the lurch for his US debut, after American foe Jarrell Miller failed drug tests a couple of weeks ago.
The likes of Luis Ortiz and Michael Hunter were rumoured to step into the breach, but Ruiz will fill in as a replacement with a month's official notice.
The Californian-born 29-year-old has won 32 of his 33 professional contests, with his only setback a razor-thin majority-points defeat to New Zealand's Joseph Parker in December 2016.
"The chills - I'm really excited for this fight," said Ruiz. "There's nervousness in me, but they're happy nerves."
He will giving away 10cm in height and many more in reach, but Ruiz Jr is bullish about his prospects of causing a seismic upset.
"I think being so tall, he fights like a big robot," said Ruiz Jr, who defeated Alexander Dimitrenko on April 20.
"I think with my style, my speed, my movement... I don't think he's fought anybody like me. It's going to be a whole different ball game."
Joshua, who has won all 22 of his contests in the professional ranks and all but one inside the distance, is unfazed by the change in opponent.
"Ruiz is a different kind of challenge, but one I embrace," he said. "Whomever is put in front of me at Madison Square Garden on June 1 (local time) will be dispatched in style.
"The rent will be collected."
Join us on June 2 (NZT) for live updates of the Joshua v Ruiz heavyweight title bout