Mayweather's trainer and uncle, Roger, derided Hatton as a "high-profile club fighter" on Tuesday, ahead of the duo's world title showdown on 8 December.

But Graham warned: "If Floyd's not concerned about Ricky, he's a fool and I don't think he's a fool.

"Their team is too experienced to underestimate Ricky. They know it's more complicated than they're saying."

Graham's comments marked the latest chapter in the lengthy pre-fight build-up to the pair's WBC welterweight title clash in Las Vegas.

Trainer Mayweather had earlier played down Hatton's challenge, giving the unbeaten Briton no chance against his nephew.

Mayweather said: "Hatton is nothing more than a high-profile club fighter and the only way he's got this reputation now is that he beat Kostya Tszyu, and that was a very even fight.

"He got away with all kinds of stuff over there (in Manchester) and he won't get away with it over here.

"What's he going to do? He's going to bring his face because that's the only chance he's got."

But Graham dismissed Mayweather's taunts and warned the American champion's camp they would be making a big mistake to regard Hatton as nothing more than another come-forward brawler.

"At some point Floyd will have to meet Ricky in the trenches and he won't be able to get on his toes," Graham added.

"Ricky's not just a pressure fighter, he's blessed with the same attributes Floyd's blessed with."

http://news.bbc.co.uk/sport1/hi/boxing/7104772.stm