Ricky Hatton says his heart will be the difference between himself and Floyd Mayweather when they meet in Las Vegas in the early hours of Sunday morning.

Hatton added Mayweather, who is defending his WBC welterweight crown, will also pay for underestimating him.

"I've never seen Floyd dig deep, grab the bull by the horns and pull a fight out of the bag," Hatton told BBC Sport.

"I'm sure he's in the best shape of his life, but he does not realise how good I am and that's going to be a shock."

The 30-year-old Hatton, unbeaten in 43 professional fights, added: "He's got to dig deep at the weekend to win.

"He thinks I'm going to be 100mph bull at a gate, but I've shown that I'm not just that and that's what's going to win it."

Hatton said a lot of boxing experts have said he is better than Jose Luis Castillo - who controversially lost to Mayweather in 2002.

"A lot of people thought Jose Luis Castillo beat Mayweather (in 2002), and Castillo in his prime wasn't as good as me," Hatton added.

"His footwork wasn't as good as mine, his footwork wasn't as quick as mine, he wasn't as physically strong as me or as explosive as me.

"Was Castillo as good a body puncher, as hard a hitter, did he have the variation of shots? I would have to say no to every one. I've got the skill, the pressure and the heart, and that's the difference.

"He's referred to me as over-hyped, fat, beer-drinking - how embarrassing for him to get beat by someone like that.

"Like Tuesday follows Monday, I swear, it all comes to an end for Floyd at the MGM Grand."