Floyd Mayweather Jr. defeats Shane Mosley in unanimous decision

Reporting from Las Vegas

Floyd Mayweather Jr. predicted a cakewalk, and Saturday night he called his own number in a brilliant rally from second-round trouble to dissect Shane Mosley in a unanimous decision before 15,117 at MGM Grand Garden Arena.

That number would be 41.

By unleashing his patented speed, precise punching and staying out of harm’s way after nearly falling to the Mosley onslaught twice in the second, Mayweather improved to 41-0, adding a victory at the same spot on the career ledger where other greats such as George Foreman, Felix Trinidad and Sugar Ray Robinson first lost.

Judges Adalaide Byrd and Dave Moretti scored the welterweight nontitle bout 119-109 in Mayweather’s favor, and judge Robert Hoyle had it 118-108.

Mosley, looking all of 38 years and even older as the fight dragged on, fell to 46-6.

“I came here tonight to give the fans what they wanted to see: a toe-to-toe battle,” said Mayweather, a six-time world champion. “It wasn’t the same style, but I wanted to be aggressive and I knew I could do it.”

Mosley buckled Mayweather’s knees twice in a stirring second round, stunning the crowd with massive rights that created a scene never before viewed in a Mayweather fight.

“Money” was in big trouble. He tried to smile off the first big blow but took another seconds later. Mosley kept on him, but Mayweather remained upright.

The question of whether Mosley could penetrate Mayweather’s superb defense had been answered.

But there was another question: Could he sustain the effort?

The answer of the night was no.

“Well, it’s a contact sport, and you’re going to get hit,” Mayweather said. “You got to suck it up and keep on fighting.”

Mosley complained that neck tightness, possibly from his 16-month layoff, dulled his ability to follow up on the damage: “I tried to move around, but he was too quick and I was too tight. I thought I had to knock him out.”

From the third round on, Mayweather reverted to his classic advantage of being able to beat the other guy to the punch. His mastery at belting Mosley with scoring rights was as impressive as any other performance the charismatic fighter has produced.

The sellout crowd at MGM Grand Garden Arena included Muhammad Ali, Gov. Arnold Schwarzenegger, Jay-Z, Paris Hilton, Diddy, Mike Tyson and several New York Jets. Mayweather, wearing a dark, fur-covered red outfit, entered the ring to the sound of gunfire-like pops and members of The O’Jays singing “For the Love of Money,” with Las Vegas characters tossing fake money to the fans.

In the seventh round, those punches turned more powerful, as Mayweather hurt Mosley with combinations, then belted him in the jaw with a right that backed the Pomona fighter to the ropes. Mayweather hurt Mosley again in the eighth, adding salt to the wound by trash-talking between the big blows. Mosley’s corner pleaded, “You trained too hard.”

So did Mayweather.

He might talk too much for many people’s liking, but Mayweather can say whatever he wants after efforts such as Saturday’s. He buried a right uppercut into Mosley’s face in the ninth, then added two more big rights while dodging Mosley’s best efforts.

The rest of the fight was a formality.

Afterward, Mayweather said in the ring that he remains willing to fight Manny Pacquiao as long as the Filipino star agrees to Olympic-style drug testing, as Mayweather and Mosley did for Saturday’s fight.

“If [Pacquiao] wants to fight, he knows where to find me,” Mayweather said. “If Manny takes the test, we can make the fight. If he doesn’t, we don’t have a fight.”

Mosley, meanwhile, said he will review the fight and “see what went wrong, take it slow and go from there.”

lance.pugmire@latimes.com