Billy Joe Saunders (29-0, 14KOs) is close to finalising a deal to face boxing's best-paid fighter Saul 'Canelo' Alvarez (53-1-2, 36KOs) in Las Vegas on May 2.
The Briton, 30, will put his WBO world super-middleweight title on the line against the Mexican on the Cinco de Mayo weekend.
Alvarez has one loss - to Floyd Mayweather in 2013 - in a 56-fight career.
WBA super-middleweight champion Callum Smith was in line for a shot at Alvarez but Saunders will instead secure his toughest bout but most lucrative to date - reportedly an $8 million pay day for BJS.
Saunders is undefeated in 29 bouts and previously held a world title in the 160lb middleweight division before moving up to acheive the same feat in the 168lb super-middleweight division.
He defended his title in a laboured knockout win over Marcelo Esteban Coceres in Los Angeles last November.
Alvarez, a man who agreed a deal worth an estimated £278m with streaming service DAZN in 2018, has held full world titles in four weight divisions. One of those was considered a minor version of a world belt at super-middleweight when he beat Rocky Fielding in 2018, which is understandably why he wants to solidify his four-weight champ status wit another worl belt at 168lbs.
The 29-year-old has since beaten American Daniel Jacobs and moved up to light-heavyweight to impressively stop Sergey Kovalev in November.
He has made no secret of his desire to set records in Mexico's already rich fighting history and a victory would ensure he can be called a legitimate four-weight world champion.
Regarded as the pound-for-pound no.1 fighter in the sport, Alvarez made his professional debut aged 15 in 2005.
During his career he has also beaten the likes of Gennady Golovkin, Amir Khan, Liam Smith and Miguel Cotto, and will start as a heavy favourite when an agreement is finalised in the coming days.