Defeated Andre​ Berto struck by Floyd Mayweather's IQ in the ring

Las Vegas: For Andre Berto, Floyd Mayweather`s boxing IQ was the most impressive attribute on show at the MGM Grand on Saturday as the five-division world champion ended his professional career with a perfect 49-0 record.

Berto, a 30-1 underdog, could do very little against his fellow American as Mayweather once again delivered a consummate tactical display in the ring to retain his WBC and WBA welterweight titles on a unanimous decision.

"He`s smart, really smart," twice former welterweight world champion Berto told reporters after being beaten for a fourth time in his last seven fights to slip to 30-4.

"He knows how to con his way in certain situations to keep his distance or to use that moment to get some rest time or to use clinches to breathe and come back with a few punches.

"I used a lot of speed but he was really crafty, he was using little things to kind of get me out of my rhythm. We pushed him to the limit but we fell short."

Berto, who described himself as a man `on a mission` during the build-up to Saturday`s fight, was asked to assess Mayweather`s standing among the pantheon of boxing greats.

"He`s sharp but it`s hard for me to say because I haven`t been in the ring with Muhammad (Ali) or (Rocky) Marciano," the American said of Mayweather, who is regarded as one of the best defensive fighters of all time.

"But right now, for him to be 38 years old and still have that speed and that timing, it`s unheard of. I definitely commend him for that.

"The run he`s had for 19 years, being world champion and continuing to move forward to greatness. As a fighter, not too many people can do that."

Many pundits have doubts over Mayweather`s insistence that his career is now over, and point to the American`s unexpected U-turn when he came back from a 21-month retirement to fight Mexican Juan Manuel Marquez in September 2009.

For Berto, Mayweather has earned the right to do whatever he wants.

"It`s up to him," he said. "I`m not Floyd. He has done tremendous things for the sport, he`s accomplished so much, he has broken all those records and made a shit-load of money.

"If he wants to retire, he can do what he wants to do. This sport is brutal by itself. 

"If he wants to retire, he should be able to. If he wants to come back, that`s on him as well."