Heavyweight world champion Tyson Fury will face MMA fighter Francis Ngannou on 28 October in Saudi Arabia.
Former UFC heavyweight champion Ngannou, 36, has no professional record in boxing.
Team Fury say the fight is not an exhibition and will “take place under the official rules of professional boxing, with three judges ringside adopting the 10-point must system”.
Fury will not be defending his WBC title in the Riyadh bout.
“This guy is supposed to be the hardest puncher in the world, but let’s see how he reacts when he gets hit by the Big GK,” Fury said, referring to his ‘Gypsy King’ nickname.
Ngannou said it was a dream come true to box Fury.
“I’ve been waiting to meet Tyson in the ring for the past three years,” he said.
“All I will say to Tyson for now is he better dance in that ring because if I touch him, he’s going to sleep.”
The WBC said it would not be involved in the fight but had granted Fury “special permission” to compete in a non-title bout as he has no pending mandatory challenger in place.
Ngannou held ambitions of being a boxer early in his career before focusing his full attention on MMA.
“This is my opportunity to make that dream come true and cement my position as the baddest man on the planet,” he said.
The Cameroonian fighter was an instant success in the UFC due to his ferocious knockout ability and became the heavyweight champion in 2021.
While Ngannou has no professional boxing background, his MMA record shows 17 wins in 20 fights, with 12 knockouts.
Ngannou has said he wants to compete in both codes, which has proven a tall ask for seasoned MMA fighters in the past.
Conor McGregor, Tyron Woodley and Anderson Silva have all struggled to adjust to the demands of boxing.
But Holly Holm successfully competed in both sports, winning multiple world championships in boxing and becoming bantamweight champion in the UFC.