Less than two weeks remain before UFC superstar Conor McGregor makes his professional boxing debut against Floyd Mayweather.

Mayweather snaps a two year retirement stint to face McGregor on August 26th in the main event of a Showtime Pay-Per-View card from the T-Mobile Arena in Las Vegas and presented by Mayweather Promotions.

In the co-featured bout, Gervonta "Tank" Davis will make the second defense of his IBF super featherweight championship against undefeated challenger Francisco Fonseca. And Nathan Cleverly will defend his WBA 'regular' light heavyweight belt against Badou Jack.

McGregor is a tremendous underdog, as he steps in the ring with a man regarded as one of the best defensive fighters in boxing history.

But McGregor feels Mayweather made a huge mistake to return to the ring at the age of 40, and after two years of inactivity.

McGregor has pulled off some shocking wins in the UFC, but he doesn't have any boxing experience and because of that the majority of all experts are predicting a one-sided contest in favor of Mayweather.

The MMA fighter is predicting something different. He says Mayweather will get knocked out cold in four rounds or less.

"I don’t know how many times I’ve shocked the world, and I’m going to shock it once again," McGregor said. "It’s not going to end well for Floyd. It’s not going to end well for all the people doubting me."

"This is a fight that has been in my crosshairs since Floyd’s been opening his mouth, simple as that. I see a beaten man in his eyes, in his body language, in everything he does. I’m going to knock him out bad, he’s too small. I know he’s fast, I know he’s got good reflexes, I know he’s experienced. I don’t care. I hit you, you fall, and that’s it. He will be unconscious.