Andy Ruiz is promising to come through with a dramatic repeat of his massive victory from June.
Anthony Joshua suffered his first career defeat and also lost his WBA, WBO, IBO and IBF belts to Ruiz in a stunning upset at Madison Square Garden in New York City.
Ruiz, who accepted the fight as a late replacement, dropped Joshua four times before the contest was waved off in the seventh round.
After a period of uncertainty, Ruiz finally agreed to face Joshua in a rematch on December 7 in Riyadh, Saudi Arabia.
Initially, Ruiz balked at the idea of facing Joshua in the country - but Joshua and his handlers, pursuant to the rematch clause, had the power to select the fight's venue and location.
Late Friday night, Ruiz took to social media and promised to end Joshua's career in the desert.
“I’m excited to announce my rematch with Anthony Joshua. In the first fight I made history and became the first ever Mexican/American heavyweight champion of the world. I am grateful to Saudi Arabia for inviting me. I took it to AJ in 'The Big Apple' and I’m looking forward to ending his career in the Desert. Don’t miss this fight," Ruiz stated.
"I will show the greatness of Mexican boxing in Saudi Arabia and in every corner of the world. Viva Mexico!"
Joshua's promoter, Eddie Hearn of Matchroom Sport, believes the unexpected location is a good move for the growth of the sport.
"We had approaches from Saudi Arabia, Abu Dhabi, Dubai and Qatar," he said.
"We wanted to go somewhere that had a vision for the sport of boxing. We already knew Saudi Arabia was for real and investing in the sport.
"We have to realise that there is another world out there outside of Cardiff and Madison Square Garden. We have an obligation to grow the sport to new areas and regions. This event could change boxing forever. If Saudi is going to invest in these fights you could be seeing a big change in the dynamics of the sport, which truly excites me."