As previously reported, British star Amir Khan will return after a year long absence against Saul 'Canelo' Alvarez in Las Vegas on May 7, the two sides announced on Tuesday.
Alvarez (46-1-1) captured the vacant World Boxing Council middleweight title last November with a unanimous decision victory over Puerto Rico's Miguel Cotto. Khan's last fight was in May 2015, a points welterweight victory over American Chris Algieri.
He said last month he had a "few options" for his next fight, but a catchweight contest at 155lbs with WBC middleweight champion Alvarez was not considered to be one of those possibilities.
Against Algieri in New York Khan improved to 31-3 with his fifth victory in a row.
Adam Smith, executive producer for Sky Sports Boxing, said: "It's a huge fight and it's come out of the blue but that's boxing, it's so unpredictable.
We thought it would be [Kell] Brook or [Danny] Garcia next for Khan, suddenly it has come to this. It's amazing. There is no doubt Canelo is a superstar in boxing. He's just 25 and he's always in very exciting fights.
"He's a lot bigger naturally than Khan. Remember, Khan was a light-welterweight who has come up from lightweight before moving up to the welterweight division, which is the division that had Mayweather, Kell Brook and [Keith] Thurman. It's a very exciting division.
"Now he is fighting at 155 it's a big risk for Amir Khan, but he obviously believes he has the speed to give Canelo Alvarez trouble. It's a mouth-watering prospect.
"We all thought that Amir Khan and Kell Brook would maybe get it on at Wembley Stadium on June 4. I know both fighters wanted it but they couldn't come to an agreement and meanwhile, behind the scenes, this was being cooked up. I mean this is a fabulous fight, it's a huge jump for Amir Khan."
