Pound-for-pound king Manny Pacquiao will fight Miguel Cotto.
The Filipino phenomenon, the Ring Magazine's light-welterweight champion will take on the WBO welterweight boss in Las Vegas on November 14, according to promoter Bob Arum.
The fight will take place at a catchweight145lbs after a Pacquiao, whose last fight was the two-round destruction of Ricky Hatton at 140lbs, agreed to Cotto's demands.
Arum's Top Rank controls both fighters and negotiations were said to be easy once Pac Man had indicated he wanted to take on the Puerto Rican.
"With Manny, you don't tell him who to fight," Arum said.
"He tells you who he wants to fight. He's not afraid of anything. There are a lot of easier guys he could fight, but he doesn't want that. He wants the best, and that's Miguel.
Unbelievable
"There's no messing about with either of these guys, and that's what's so exciting.
"That's why it's an unbelievable fight, with two guys who really love to fight and don't dance around."
The fight was first mooted for Madison Square Garden, New York, where Cotto regularly performs in front of full houses, but will now take place at the MGM Grand Garden.
It will be only the second time Cotto has fought in the fight capital in five years, his last outing there being his 11th-round defeat at the hands of Antonio Margarito last July - after which the winner was suspended for illegal handwraps.
For Pacquiao it will be his sixth straight appearance in Vegas, where he has beaten Marco Antonio Barrera, Juan Manuel Marquez, David Diaz, Oscar de la Hoya and Hatton to shoot to the top of the pound-for-pound rankings.