Floyd Mayweather Jr. scores unanimous decision against Miguel Cotto

Floyd Mayweather improves to 43-0 Saturday night after a 12-round bout ends with unanimous decision vs. Miguel Cotto (r.)

Floyd Mayweather Jr. hadn’t been pushed to the limit in more than a decade, since Jose Luis Castillo waltzed him around the ring as a junior lightweight in 2002. Since then Mayweather has been on cruise control as he has sailed to the top of the boxing world.

Miguel Cotto (37-3, 30 KOs) gave Mayweather as much as he could handle, but in the end it wasn’t enough as Mayweather scored a hard-fought 12-round unanimous decision to take away Cotto’s WBA super welterweight title before an electrified crowd at the MGM Grand Garden Arena on Saturday night.

(R-L) Floyd Mayweather Jr.throws a right to the face of Miguel Cotto during their WBA super welterweight title fight at the MGM Grand Garden Arena on May 5, 2012 in Las Vegas, Nevada.

Judges Patricia Morse Jarmin and Dave Moretti scored it 117-111 and Robert Hoyle scored it 118-111, all for Mayweather. The Daily News scored it 117-111 for Mayweather.

Right after the fight ended, Mayweather said to Cotto, “You’re a hell of a champion. You’re the toughest guy I ever fought.

“Look, when fights are on Pay-Per-View you want to give the fans what they paid for and that’s excitement,” Mayweather added. “It comes with the territory when you fight a future Hall of Famer like Miguel Cotto. I had to fight hard, I had to suck it up. I knew I would have to come into the fight and fight hard. He came to fight, not to survive. I dug down and I fought him back.”

Mayweather (43-0, 26 KOs) was walked into the ring by pop star Justin Bieber and rapper 50 Cent. The crowd, which had booed Mayweather previously when he was shown entering the arena before the fight, didn’t boo when he walked to the ring.

This night was made possible by Justice of the Peace Melissa Saragosa, who postponed Mayweather’s 90-day jail sentence so that he could fight Cotto. Mayweather will have to report to the Clark County Detention Center on June 1 to begin serving that sentence, which stemmed from his guilty plea on a domestic abuse charge.

On going to jail on June 1, Mayweather said: “It comes with the territory. In life there’s obstacles, and I take the good with the good and the bad with the bad. I’ll deal with it.”

Mayweather quickly established his superiority in speed, quickness and defensive slickness. The first half of the second round was spent with Mayweather fighting with his back against the ropes in his corner, ducking, slipping and catching punches as Cotto flailed away. Mayweather would fire a few quick uppercuts just to let Cotto feel his presence.

(L-R) Miguel Cotto throws a left punch at Floyd Mayweather Jr. during their WBA super welterweight title fight at the MGM Grand Garden Arena on May 5, 2012 in Las Vegas, Nevada.

Even though he spent most of the fight right in front of the Puerto Rican champion, Mayweather proved an elusive target. Cotto landed his first clean shot of the fight in the fifth round — a sharp left hook — as Mayweather’s back was pinned to the ropes. It was a start. Later in the round he bloodied Mayweather’s nose with a straight left. Mayweather acknowledged the shot by stepping back and smiling.

Cotto had his finest round in the eighth as Mayweather began to slow enough for Cotto to find his range and land. This time when he pinned Mayweather against the ropes, Cotto was able to pummel him in the chin with straight lefts and looping rights. When Mayweather was seated on his stool in his corner between rounds, the big screen flashed a picture of his face smeared with blood from his nose, and the crowd cheered. The fans thought that Mayweather, the pound-for-pound king, was finally getting his licks.

The crowd cheered “Cotto! Cotto! Cotto!” near the end of the ninth round. He had won the crowd, but the real question was whether he had done enough to win on the judges’ scorecards.

Late in the 12th round Mayweather buckled Cotto’s knees with a sharp right uppercut. Cotto lurched forward into Mayweather’s arms and stayed on his feet. The crowd was on its feet as Cotto had given Mayweather the first real test that he’s had since Castillo pushed him to the limit as a junior lightweight more than a decade ago.

“I tried to make the (Manny) Pacquiao fight and that didn't work, so I fought Miguel Cotto instead and gave the fans a great fight,” Mayweather said. “I’m just trying to fight Pacquiao. I want that fight. If he takes the (drug) test I will fight him. Miguel Cotto agreed to the test.”

Cotto left the ring without commenting.

In the co-feature of the evening, Saul (Canelo) Alvarez (40-0-1, 29 KOs) pounded out a lopsided 12-round decision over Shane Mosley to retain his WBC super welterweight title. Alvarez, 21, was 7 years old when the 40-year-old Mosley (46-8-1) won his first title.