The Straight Blast Gym head-coach tweeted "10 weeks #McGregorVsMayweather" alongside an image of himself and The Notorious One.
The long-anticipated fight, which pits two of the top-selling fighters in the world, was announced by both Mayweather and McGregor on Wednesday.
The contest, nearly certain to be the biggest grossing event in boxing history, was confirmed on Wednesday and is set to take place at the MGM Grand Garden in Las Vegas on August 26. He left the sport in 2015, the same year he defeated Pacquiao via unanimous decision in what went down as the richestfight in boxing history.
FOX Sports UFC analyst Yves Edwards: "Conor McGregor is making his boxing debut in what could be the biggest fight in boxing's history".
McGregor, the UFC's reigning lightweight champion and former featherweight champion, is known as much for his bravado as for his explosive knockout power inside an MMA octagon.
No conformation has been provided at this time from Mayweather Promotions, UFC, Showtime or the fighters.
Incredibly, the Daily Star recently claimed that McGregor wanted a $100 million purse to take on the undefeated Mayweather.
LAS VEGAS (AP) - It may not be the fight of the century, but it could be the event of at least the last few years.
The Irishman is arguably the biggest selling pay per view star in combat sports now, but will be fighting in his first boxing bout against one of the greatest boxer's of all time.
On Mayweather agreeing to the fight: "I always say this about Conor, and now you can say it about Floyd, too".
"I talked to Conor McGregor this morning", White said. It will take place at 154 pounds.
At this point, we have an early prediction from the bookmakers, which are saying that Floyd Mayweather is a favorite, but in an unusual match like this one, we have to add that there are no underdogs and favorites.
Injured Dettori pulls out of Royal Ascot
Dettori says it is "soul destroying as it's the most important week of the year". "In racing, there's no winning post". She topped the ensemble off with a dainty little hat because even if you're a royal, you've still got to be sun smart.
Kevin Durant Shows DC Love After NBA Championship Win
Kerr returned for game two of the Finals and wins his second title in three years. "I'm just so happy to be a part of it". In 2011, he would return to the Finals as a member of the Heat, losing to the Dallas Mavericks in six games.
No comeback this time for Kristina Mladenovic
She added: "I think the magic has always been happening for me here, even the first time I came here as a little kid". Instead of rolling over though, she fought back to book her place in the quarter-finals with a 2-6, 6-2, 6-4 victory.
Thomas shoots 63; breaks US Open record
Fowler, who shared the 36-hole lead at the Masters in April, never came seriously close to bogey because he was never in trouble. He had a six-shot lead at the turn but hit only three fairways on the nine and missed a 4-foot par putt on the 18th for a 70.