Anthony Joshua is set to take on Andy Ruiz Jr as he makes his US debut at Madison Square Garden on June 1.
The heavyweight star was due to defend his WBA, WBO and IBF belts against Jarrell Miller before the American tested positive for three banned substances.
Promoter Eddie Hearn quickly drafted a shortlist of potential replacements featuring the likes of Luis Ortiz, Michael Hunter and Manuel Charr.
But according to Fox Sports Boxing Insider Mike Coppinger, it is Ruiz who has got the nod and "agreed terms" to fight Joshua at short notice at New York on a huge night.
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Ruiz has a 32-1 record with his sole defeat coming with a controversial points loss against Joseph Parker for the vacant WBO title back in December 2016.
Joshua has since won that belt from Parker, whilst Ruiz has rebuilt his career with a trio of wins including a five-round demolition of Alexander Dimitrenko just last weekend.
Having gone through training camp to fight Dimitrenko, and with the fight not going the distance, he is well-placed to step in at relatively short notice with Joshua already midway through his training camp.
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Eddie Hearn recently talked up the fight and backed Ruiz to come to fight rather than simply rolling over to allow Joshua to win.
"I like the fight for many reasons," Hearn said.
"Aesthetically, Andy doesn't always look the best, but he can fight.
"He's fast, he'll be there to win, he's going to have a big Mexican support."
