Marcos Maidana did everything but beat Floyd Mayweather Jr., taking him 12 tough rounds before losing a majority decision at MGM Grand in Las Vegas.

Mayweather remained unbeaten Saturday night, but not by much. Maidana swarmed all over him from the opening bell and gave him perhaps his toughest fight in a 16-year professional career.

In the end, though, Mayweather got the win — just as he did in his previous 45 fights. He retained his welterweight title by winning 117-111 on one scorecard and 116-112 on another. A third judge had it even at 114-114.

The Associated Press scored it for Mayweather 115-113.

Maidana threw far more punches, but Mayweather was more accurate with his as the two battled into the late rounds with the fight still very much in doubt. Cheered on by a large contingent of Argentine fans, Maidana took the fight to Mayweather, who was cut by the right eye in the fourth round by an accidental head butt.

"It was a tough, competitive fight," Mayweather said. "I normally like to go out there and box and move. But he put pressure on me. I wanted to give the fans what they wanted to see so I stood and fought him.

Maidana raised his arms in victory when the final bell sounded, and Mayweather watched pensively from his corner as the scorecards were added up before he was declared the winner.

"I think I won the fight," Maidana said. "He didn't fight like a man."

Punch stats by Compubox showed Mayweather landing 230 of 426 punches to 221 of 858 for Maidana. It was the most punches landed by any fighter against Mayweather in 38 fights where punch stats were compiled.

"I couldn't see for two rounds after the head butt," Mayweather said. "After I could see again it didn't both me. That's what champions do, they survive and adjust."

Amir Khan vowed to be impressive on the undercard, and he was.

The Briton knocked Luis Collazo down three times Saturday night on his way to a lopsided decision win he needed desperately if he hopes to fight Mayweather. In his first fight in more than a year, Khan dominated against a former champion while looking sharp at his new weight.

Khan lost out to Maidana to fight Mayweather, but made the best out of his spot at the top of the undercard for  by beating and bloodying Collazo.

"People want to see that fight between me and Floyd," Khan said.

Khan, who said he was starving himself to make 140 pounds, was cautious with Collazo, but used his hand speed from the outside to land right hands to the head from the first round on. He dropped Collazo with a right hand in the fourth round, then dropped him twice in the 10th round.

Collazo finished the fight, but he was bleeding from a cut by his right eye and his face was swollen from Khan's right hand. Two judges scored it 119-104, while the third had it 117-106.

Khan's dominance was shown in punch stats that showed him landing 264 of 692 to 140 of 511 for Collazo.

"I had to hang in there," Collazo said. "You have to take me out, that's what it's all about."

Khan, who improved to 29-3, thought he was going to be fighting Mayweather instead of Maidana. He gave up a title fight in December to wait for Mayweather, but didn't get picked for the fight despite winning an online poll conducted by Mayweather.

"It was very hard because Collazo is really awkward," Khan said.

In another fight, Adrien Broner came back from his only professional loss to win a lopsided decision over Carlos Molina in a 140-pound bout.

Broner was simply too fast for Molina, who pressed the action but was consistently beaten to the punch. Broner never seemed to hurt Molina, but won all 10 rounds on one scorecard and won easily on the other two.

"As you can see I didn't have any trouble," Broner said. "It was sparring on national television."

Broner was fighting for the first time since being beaten by Maidana in a December fight, when he was knocked down twice and lost a decision. That fight was at 147 pounds, but Broner moved back down to 140 to fight Molina.

Broner (28-1, 22 knockouts) said he felt better at the lower weight after briefly holding a piece of the welterweight title. Ringside punch stats showed him landing 237 of 614 punches to 150 of 550 for Molina.

"This is definitely the ring weight," he said. "I'll fight anybody, but I want to fight (Manny) Pacquiao before he leaves."

In another bout, J'Leon Love came back from a fifth round knockout to beat Marco Antonio Periban in a 168-pound fight.

Love won a 10-round decision on all three ringside scorecards to remain unbeaten in 19 fights. Periban fell to 20-2-1.