As UFC star Conor McGregor and boxing legend Floyd Mayweather move closer to finalizing a mega-fight, many athletes in the fighting world are starting to weigh in with what they think will happen if and when the two stars face off.

The bout will almost certainly be a boxing match, with McGregor stepping into Mayweather's world to battle the 49-0 legend on his turf.

However, according to UFC star Georges St-Pierre, that potential matchup could just be the beginning of the McGregor-Mayweather rivalry.

According to a Q&A with RT.com, St-Pierre believes McGregor will push for an MMA fight against Mayweather regardless of whether he wins or loses in the boxing ring:

"If he loses, and I’m pretty sure he’s going to lose if it happens, the odds are not in his favor," St-Pierre said. "But if he manages to survive, it could be like a win for him. Because after he’s going to start talking, ‘Hey, I’ve stepped into your game, why don’t you step into mine?’ So it depends not only on the result, but how it’s done. It all depends on how things play out."

St-Pierre's theory makes sense, though it would be hard to imagine a 50-0 Mayweather accepting a challenge to fight McGregor in the octagon, regardless of how much trash the Irish fighter talks.

Though St-Pierre thinks the epic fight will eventually happen, he's not giving McGregor much of a chance to pull off the major upset:

"I think it will happen," he said. "I don’t think he’s going to win, I don’t think he’s going to win at all, but I think he wants to do it and he’s going to make a lot of money out of it."

McGregor needs to finalize a deal with Mayweather soon, or else he'll likely have to forfeit his UFC lightweight title. That could be interesting as GSP has been linked to a potential run at the lightweight title.

For now, though, GSP - the former welterweight champion - has his sights set on middleweight champion Michael Bisping. The fight has been in the works for months, but, according to FOX Sports, Bisping is unhappy with the delays in setting a date:

“If he wants to wait until September or October then he can go find himself another opponent, buddy. Because I call the shots,” Bisping said. “Without sounding like an [expletive], it’s my belt I’m the champion and I’m not willing to sit around until September or October. This fight was discussed in January. A fight camp only takes eight weeks or six weeks. Fighting in September or October is ridiculous.”

If St-Pierre wants to become the first fighter to win titles at three different weight groups, he needs to focus his full attention on Bisping. Otherwise, it seems, he'll likely be passed up for a matchup against McGregor when he returns to the UFC.