The drum beats grow louder for a massive-money showdown between Floyd Mayweather and Conor McGregor.

Mayweather announced Saturday in England, where he's been on a publicity tour, that he's "coming out of retirement just to fight Conor McGregor."

“I don’t want to hear no more excuses about the money, about the UFC," Mayweather, 40, said in a video posted by FightHype.com. "Sign the paper with the UFC so you can fight me in June. Simple and plain, let’s fight in June.

"You’re the B side. I’m the A side. We’re not here to cry about money. I’m tired of all this crying about money and saying you want to fight. You’re blowing smoke up everyone’s ass, if you want to fight, sign the paperwork.”

Mayweather and McGregor have been going back and forth for months about the proposed superfight. At first, it seemed like a pipe-dream, perhaps even a publicity stunt.

But the talk continues to grow louder. And if Mayweather is serious, just maybe the boxing match against the UFC lightweight champion gets done.

Of course, with two massive egos in the negotiating room, petty deal points will be fought tooth-and-nail, aside from the No. 1 matter: money.

“When I faced Arturo Gatti, I went to his turf,” Mayweather said, referring to his first pay-per-view main event. “He was the A side. I was the B side. I beat him. I didn’t cry. I didn’t complain. When I faced Oscar De La Hoya, he was the A side and I was the B side. I didn’t cry. I didn’t complain. I beat him and I became the A side."

It's clear this fight won't get done unless McGregor concedes on a few matters. Mayweather isn't going to walk to the ring first. He's not going to be second on the billboard. And he's surely going to want the lion's share of the purse.

Mayweather claims he didn't even know who McGregor was when the Irishman first called him out last year. But "Money" knows who he is now. And with sacks of money – likely hundreds of millions – awaiting him for what should be an easy night's work, Mayweather is ready to end his second retirement and go for that 50th win.

Now it's McGregor's turn to further build up a fight that may never happen.