Floyd Mayweather celebrates after defeating Andre Berto in their WBA/WBC welterweight title bout at MGM Grand Garden Arena in Las Vegas.

AFP/Las Vegas

Floyd Mayweather earned a unanimous decision over Andre Berto on Saturday to claim his 49th and he says final victim in a glittering unbeaten ring career spanning two decades.

All three judges ruled overwhelmingly in Mayweather's favor and afterwards the American welterweight world champion confirmed that he was retiring, saying: "My career is over.

"It's official."

He equals the perfect 49-0 record of heavyweight legend Rocky Marciano and retains his WBA and WBC titles, embellishing his reputation as the best boxer of his generation.

Mayweather fell to his knees in the ring after the bell, taking in the moment.

"I want to thank all the fans... for 19 years I would not be able to do it without these fans," he said, after the judges ruled it 118-110, 117-111 and 120-108, all to the champ.

"But you have to know when it's time to hang it up. I'm knocking at the door; I'm nearly 40 years old now.

"There's nothing else to prove in the sport of boxing. I'm leaving the sport with all my faculties; I'm still sharp and smart."

The 38-year-old self-styled "TBE" ("The Best Ever"), who had consistently said that the Berto showdown would be the last time he steps into the ring, had too much guile and nous for the rank outsider.

Berto, who has now lost four of his last seven fights, was set up as the fall guy for the pound-for-pound king's coronation - and he played the role perfectly, showing plenty of heart but not quite enough quality.

Mayweather has his critics, but he was given a hero's welcome at the MGM Grand Garden Arena in Las Vegas by a boisterous crowd who had come expecting to see him give Berto, 32, an old-fashioned shellacking.

He did not quite do that, but instead used his sublime defensive skills to avoid the worst that Berto - a former two-time world champion - could throw at him.

Berto kept coming at Mayweather; Mayweather would land a quick-fire combination and then dart out of trouble again - to roars of approval for the man fans have taken to calling simply "Money."

Turning the screw  

Even when he had Mayweather against the ropes Berto found it hard to connect with anything meaningful.

The first real taste of a fight breaking out came at the end of the second round, when the two tangled after the bell, Mayweather giving his foe a dirty look.

The champion - hit by claims on the eve of the fight that he broke anti-doping rules earlier this year, which he denies - came out for round three clearly still riled.

Mayweather was sent scampering across the canvas after one exchange, bringing the crowd of 13,395 to its feet, but the move was more akin to wrestling than boxing.

Berto had his first real taste of success halfway through the fourth of the scheduled 12, forcing Mayweather to cower against the ropes as Berto chased one of the biggest upsets in boxing history.

Berto resorted to roughhouse tactics in the fifth, catching Mayweather with one particularly low shot that drew oohs from the stands.

The crowd were up on their feet again in the sixth as Mayweather turned the screw, bamboozling the underdog with three shots to the body in rapid succession.

Still Berto - dismissed as a dud by some critics who wanted to see Mayweather take on a bigger name - kept coming forward.

But he was mostly finding air, not Mayweather's face, and Mayweather punished him in the closing seconds of the seventh, and Berto briefly looked in big trouble.

Mayweather was ominously gaining control and he knew it - striking a pose at the end of the eighth, and some in the crowd serenaded him with cries of "TBE! TBE!"

Referee Kenny Bayless had to stop the action in the 10th and warn the pair to stop mouthing off at one another, and there was another flashpoint when the bell sounded.

Mayweather sealed his night's work - and that of his career, if he is to be believed - by turning showman in the 11th, ducking brilliantly to avoid several Berto haymakers and then looking behind himself as if to say mockingly to his opponent: where am I?

Asked what he and Berto were muttering to each other in the ring, Mayweather said: "Just trash talking."