Floyd Mayweather and Andre Berto
Floyd Mayweather has hit back at critics of his decision to handpick Andre Berto for the final fight of his astonishing career after Amir Khan claimed the five-division world champion was 'scared' of him.

Mayweather says he will retire with a 49-0 record after his September 12 meeting with Berto at the MGM Grand in Las Vegas, a fight that many are already labelling a mismatch.

Khan and Keith Thurman both fancied a pop at the 38-year-old's unbeaten record but Mayweather says Berto will push him to the limit and claims neither Khan, nor Thurman are ready to face him.

'You look at the junior middleweight and the welterweight division,' Mayweather said. 'The two divisions: one division I'm undisputed champion at... The other division I hold two titles at.

'There’s one man that stands all alone, Floyd Mayweather. So I looked at the division, I looked and said "who’s always in a tough, exciting fight, who has quick hands, who’s a boxer puncher, who always give it 100 per cent every time they go out". (It's) Andre Berto.' 

Questioned over why he turned down Khan's advances to fight him, 'Money' said: 'Amir Khan has to get past Danny Garcia first. Once Amir Khan can get past Danny Garcia then the fight would’ve happened but that’s not my focus.'

With Mayweather adamant that his September blockbuster will be his career finale, provided sport's highest earner is telling the truth, Khan's chance will come too late.

The 28-year-old Brit was knocked out in a fourth-round stoppage against Garcia in 2012 and says he has been snubbed by the WBA light welterweight champion over an offer for a rematch.