Floyd Mayweather vs Conor McGregor could happen, believes Showtime vice-president Stephen Espinoza

Floyd Mayweather’s suggested return against UFC champion Conor McGregor would require an "unprecedented deal", according to Showtime boss Stephen Espinoza.

The US-based boxing mogul is optimistic that the unique fight could come to fruition, despite the complications bringing the retired Mayweather into the ring with McGregor, who is contracted with the UFC and has never boxed professionally.

"It would take an unprecedented deal to make this happen - we've seen unprecedented deals that allowed mega-fights to happen before," Espinoza exclusively told Sky Sports.

It would take an unprecedented deal to make this happen - we've seen unprecedented deals that allowed mega-fights to happen before

"It's an uphill battle, simply because it's never been done before. But we have two potential combatants who are interested and motivated in making it happen, plus tens of millions of people around the world who are eagerly anticipating the match.

"I hear the criticisms and the public outcry that it may be one-sided but I don't necessarily agree.

"We can go through the history - there were fights that were uniformly expected to be one-sided but, when they happened, there was a much different result. The Oscar De La Hoya-Manny Pacquiao fight was criticised but it turned out differently.

"It's no foregone conclusion that this is a Mayweather victory - yes, he is one of the most skilled boxers of modern times but McGregor has his own set of assets and strengths."

Espinoza's Showtime were instrumental in making Mayweather's defining win in 2015 against Manny Pacquiao after protracted negotiations.