According to multiple sources, including Yahoo Sports and the Las Vegas Review Journal, a deal has been reached for former five division world champion Floyd Mayweather Jr. (49-0, 26 KOs) to come out of retirement for a boxing match with UFC champion Conor McGregor on August 26 in Las Vegas.

The date, requested by Mayweather Promotions for a Showtime event, was approved on Wednesday morning by the Nevada State Athletic Commission.

Mayweather, 40-years-old, retired from boxing in September 2015 after dominating Andre Berto over twelve rounds. The McGregor fight will either take place at the MGM Grand or the T-Mobile Arena. Mayweather Promotions reserved the MGM, but the venue could change to the T-Mobile.

When talk of the fight was first discussed last year, many felt it was a bad joke - but the amount of money involved - at least $100 million for both athletes - made both sides come together for serious negotiations.

Last month, the Irishman has struck a deal with the UFC and company president Dana White to allow him to compete in the one-off megabucks event.

McGregor took to social media on Sunday, advising his followers that something very big was on the horizon.

Besides placing a hold on the MGM for August 26th, Mayweather's promotional company has also reserved the arena on August 25 for a weigh-in.

The main event and the unannounced undercard fights the following evening will be carried on pay-per-view as part of a joint effort by UFC and Showtime, Mayweather's long-time broadcaster of choice.

Fighters from the Las Vegas resident's stable are expected to feature on the undercard, including Badou Jack, who could face WBA world light-heavyweight champion Nathan Cleverly. And a voluntary defense by IBF super featherweight champion Gervonta Davis.

McGregor, who has not fought since he won the UFC lightweight title last November, recently became a father for the first time. He has never boxed professionally having switched to mixed martial arts as a youngster.