Floyd Mayweather Favored vs. Conor McGregor in Opening Odds

Undefeated boxer Floyd Mayweather Jr. will open as a definitive betting favorite over UFC's Conor McGregor if their fight becomes official.

Joe Osborne of OddsShark passed along the opening lines: Mayweather (-750), McGregor (+475).

On Thursday, the 28-year-old Irish MMA star released a statement to John Balfe of TheMacLife.com confirming he signed an agreement to take part in the fight. No further details about the possible bout were immediately revealed.

"It is an honor to sign this record-breaking deal alongside my partners Zuffa LLC, the Ultimate Fighting Championship and Paradigm Sports Management," McGregor said. "The first and most important part of this historic contract has now officially been signed off on. Congratulations to all parties involved. We now await Al Haymon and his boxer's signature in the coming days."

In January, Mayweather said during an appearance on ESPN's First Take he wanted a nine-figure payday in order to take part in the cross-sport clash.

"We tried to make the Conor McGregor fight," Mayweather said. "They know what my number is. My number is a guaranteed $100 million. That was my number."

The discussion around the fight has been consistent: Whichever athlete received the "home-sport advantage" would be a sizable favorite.

"This fight is a long shot to happen, in my opinion, and McGregor is a bigger long shot if it does happen," Bovada sportsbook manager Kevin Bradley told OddsShark. "Floyd has never really been hit his entire career against the baddest professional boxers in the world, so Conor will have to shock the world to even lay some leather on Mayweather."

Even UFC foe Jose Aldo, who lost to McGregor in 13 seconds at UFC 194, didn't give McGregor a chance, according to Guilherme Cruz of MMA Fighting.

"First of all, we don't know if it will happen or not," Aldo said in February. "There are a lot of things involved, mainly McGregor has a contract to follow so it's hard to happen, but if it happens, I don't think he has a chance."

The odds will likely shift even more dramatically in Mayweather's favor if he signs the contract to finalize the deal. He'll hold a massive tactical advantage inside a boxing ring.