Former undisputed heavyweight champion Mike Tyson has revealed Andy Ruiz Jr is more than capable of repeating his big upset performance against Anthony Joshua back in June.

The 29-year-old Mexican shocked the world when he dropped Joshua four times en route to securing a seventh round stoppage victory, and in the process captured the WBA, WBO, IBF and IBO world titles in front of a packed crowd at Madison Square Garden in New York.

The outcome was regarded as one of the biggest upsets in the history of the heavyweight division, rivalled only by Tyson’s 1990 knockout loss to Buster Douglas.

Tyson, who at the age of 20 became the youngest boxer to be crowned heavyweight champion, was very impressed with Ruiz’s victory.

“Andy came and saw me the other day, we talked. His energy is wonderful, he is a beautiful person,” Tyson said per The Mirror.

“If he did it once, he can do it again!”

The rematch between Ruiz and Joshua will take place by the end of the year, despite conflicting reports that both sides are struggling to come to an agreement over the location.

Joshua has exercised his right to an immediate rematch and would ideally like the bout to take place in the UK, whereas Ruiz is demanding they touch gloves again in either the US or Mexico.

Joshua’s promoter Eddie Hearn is well aware that Ruiz and his handlers are not in favour of having the fight on UK soil, but remains confident that The Principality Stadium in Cardiff will host the titanic rematch, with a tentative date of December 14 pencilled in.

AJ still hopes to have the backing of the home crowd and spoke to Sky Sports News on where he envisions the fight taking place and the outcome.

“It’s fine I don’t mind fighting him in America. I’ve done it before, but I’d love to fight here because I had no reason to go in the first place,” Joshua said per The Mirror.

“I went there off my own back, so for the rematch now, I wold love it to be in Cardiff, however, if it’s going to be on neutral ground, Ruiz is the champ, we’ll kind of make some calls as well in that situation.

“To be honest I’d fight in Tijuana and Ruiz’s uncle could be the referee and I would still whoop him.

“But walking out in front of 70, 80, 90,000 people screaming and rooting for you to win, that type of energy that goes through your body is unstoppable, and I think that could give me that little bit of edge I need to win those belts back.”

Ruiz answered by posting the following statement to his 116,000 Twitter followers: “AJ says he can ‘whoop’ me in Tijuana; prove it, let’s run it in Mexico. Remember that you did have a huge reason to come to America and that was to build your profile.”