Floyd Mayweather: On paper Conor McGregor has the edge... I'm not what I used to be

After spending much of the past month mocking the skills of his opponent – a UFC lightweight champion who has agreed to a straight boxing bout – the American has changed his tone.

The 40-year-old pointed to McGregor’s size and relative youth as assets he could use in their upcoming fight.

"He's a lot younger,” Mayweather said of his 29-year-old opponent. “When you look at myself and Conor McGregor on paper, he's taller, has a longer reach, he's a bigger man from top to bottom. He's a lot younger, so youth is on his side."

The American, who has a 49-fight unbeaten record, also said his lack of recent practice could be a problem. He told ESPN: "I've been off a couple of years. And I'm in my 40s. So, if you look at everything on paper, it leans toward Conor McGregor."

Despite McGregor making his professional boxing debut in the Las Vegas fight, Mayweather did not write off the Irishman’s chances. "I'm older,” added Mayweather.

"I'm not the same fighter I was two years ago. I'm not the same fighter I was five years ago. I lost a step," he said. "A fighter like Andre Berto isn't even supposed to go the distance with Floyd Mayweather, but remember, I was 38. It's obvious I'm slipping a little bit to even let a fighter like that go the distance with me.

The American, who is known for his defensive skills, also promised that the fight would live up to its billing after his 2015 bout against Manny Pacquiao lacking much of the anticipated drama.

"This can't be a defensive fight. I have to go to him," Mayweather said of McGregor. "I owe the public because of the Pacquiao fight. They weren't pleased with that. They're gonna be pleased with this fight here."