Speed was the name of the game Saturday night.

Floyd Mayweather had it, and Sugar Shane Mosley didn't have enough to escape it. And Mayweather overcame a shaky second round to easily win a unanimous decision victory against Mosley in their welterweight mega-fight before a crowd of 15,117 at the MGM Grand Garden Arena.

Mayweather, who came into the fight a 4-1 favorite to remain undefeated, improved his record to 41-0, with 25 knockouts, while Mosley fell to 46-6 (39 KOs).

It was pretty much a one-sided affair after the second round, which was the only one Mosley won for two of the three judges at ringside. Adelaide Byrd and Dave Moretti scored the fight 119-109, while Robert Hoyle scored it 118-110, all for Mayweather.

"I did what the fans came here to see — a toe-to-toe battle," said Mayweather. "That's not my style, but I wanted to give them that."

Mayweather said he went over the game plan while sitting around the house with his uncle (trainer Roger Mayweather) and father (Floyd Sr.).

"They wanted me to box, and then lay on the attack," Mayweather said. "We should've pressed the attack earlier."

Mayweather's speed and mostly impenetrable defense was the difference. He was in control in all but the second round, when Mosley came out swinging and connected on several power punches, at one point staggering Mayweather, whose knees buckled.

The sight of Mayweather appearing hurt got the crowd excited, and they began chanting "Mos-ley, Mos-ley." But Mayweather held on until the bell rang.

"It's a contact sport and you're going to get hit. But you got to suck it up and keep on fighting," said Mayweather. "That's what I did when I got hit in the second round."

Mosley, who had not fought in 16 months coming into the fight, cited ring rust as one possible reason for his sluggish performance.

"I still feel really good but my neck was really tight," he said. "I think the long layoff hurt me. I caught him with a big right hand (in the second round) and I tried to move around but he was too quick and I was too tight.

"After I landed the right hand I thought, 'I need to knock him out but I need to do it now.

"Maybe when I landed that big shot, I got gung ho and went to land another big shot. There were a lot of different things that were going on there."

Mosley wasn't sure what was next for him as far as fights are concerned. "I'm happy I got this fight, but I'm going to go home and review the tapes and take it slow from there," he said.

I'm going to take a little vacatgion, relax and enjoy myself."

Mayweather addressed the question of whether he would be willing to fight pound-for-pound king Manny Pacquiao next.

"If Pacquiao wants to fight, it's not that hard to find me," Mayweather said. "If Manny takes the (blood test), we can make the fight happen. If he doesn't we don't have a fight."

"Mosley was a warrior, I'm glad I got to fight him., but he also did what I asked him to do (accept the blood testing), and If every athlete in the sport of boxing could pay attention to us, I'm willing to take the chance."

Whether it's Pacquiao or whomever, Mayweather said, "I'm going to continue to keep on fighting the best. Shane Mosley is a hell of a fighter."

By the fourth round, Mosley had stopped creating his offense and Mayweather seemed to have figured his opponent out.

Mayweather's speed began to overwhelm Mosley in the middle rounds as he repeatedly connected on power shots to Mosley's face. Mosley wasn't fighting back much and appeared winded in the seventh round, one of Mayweather's best rounds.

In the seventh round, Mayweather began to land punches at will, and said to Mosley, "let's fight. You said I was going to do all this different running, and I didn't come to fight, That's all I was basically saying."

It was another big round for Mayweather.

Mayweather brought the crowd to its feet in the 10th round as he continued to pound Mosley, and appeared to hurt the champion near the end of the round. The crowd chanted Mo-ney! Mo-ney!

Mosley came in as the WBA welterweight champion, but Mayweather chose not to fight for the title, refusing to pay the bout's sanctioning fee. It's unclear what will happen to the WBA title since Mosley lost.

Mayweather, nicknamed "Money," entered the ring to several loud explosions, and the O'Jays singing For the Love of Money with confetti in the firm of fake dollars bills floating through the air. He said afterwards it was his idea, and also his idea to keep Mosley waiting in the ring for awhile, waiting for Mayweather to leave his locker room.

The fight came about as a result of Mosley's opponent, Andre Berto, pulling out of their scheduled Jan. 30 welterweight title fight when the tragic earthquake struck Haiti on Jan. 12. Berto cited exhaustion after he lost several relatives in the quake.

Mayweather's proposed megafight against Pacquiao, scheduled tentatively for March 14 in Las Vegas, fell through after Pacquiao refused to bow to Mayweather's demand for Olympic-style blood-testing.

Pacquiao field suit against the Mayweathers and Golden Boy Promotions for defamation of character after they accused him of taking performance-enhancing drugs.

Mosley, who agreed to the blood testing, was guaranteed at least $7 million for the fight, while Mayweather was guaranteed more than three times as much, $22 million.

In the main undercard event, Mexico's brilliant, young Saul "Danelo" Alvarez, 19, struggled in the first round, nearly going down, before coming back strong to stop Jose Miguel Cotto at 2:51 of ninth round. Alvarez landed 36 power shots in the round, most of them flush on the head of Cotto before referee Tony Weeks called the fight.

Alvarez (32-0, 24 KOs) nearly went down in the first round after and onslaught of punches from Cotto (31-2-1, 23 KOs) and was wobbling after being caught in the corner several times. But he survived the round.

"It was just a matter of time," said Alvarez, who connected on 194 power punches, to Cotto's 91.

"The first round was scary, but I gained my confidence as the round went on.

"This is the first time Cotto's been stopped because he's never fought anyone as tough as me."