Britain's Nathan Cleverly will defend his WBA light-heavyweight title against Badou Jack on Saturday, 26 August.
The bout will take place on the Floyd Mayweather v Conor McGregor undercard in Las Vegas.
Welshman Cleverly said: "I've trained long and hard for this fight and I'm ready to be let off the leash. This is the biggest fight of my career."
Swede Jack, 33, is based in Las Vegas and has 12 knockouts in 21 wins, with one defeat and two draws.
Cleverly, 30, won the title by beating Juergen Braehmer in October 2016.
Jack's super-middleweight unification fight with Britain's James DeGale ended in a controversial majority draw in January 2017.
He is moving up a weight after holding the WBC super-middleweight crown for two years.
Jack said: "I'm getting ready to take that belt, and win a title in my second weight class."
If Cleverly - whose record is 30 wins, including 16 knockouts, and three defeats - wins, he must defend the belt against Russian Dmitry Bivol.
According to WBA rules, a champion has 120 days to fight a mandatory challenger, and that deadline has expired.
Russian Bivol, 26, claimed the interim championship in May 2016 by defeating Felix Valera, and has won all 11 of his professional bouts.
The World Boxing Association says Cleverly and Bivol's teams have 30 days - from 27 July, 2017 - to reach an agreement or the fight will be called to purse bids.
Get all the latest boxing news sent straight to your device with notifications in the BBC Sport app. Find out more here.