LAS VEGAS -- Pound-for-pound king Floyd Mayweather Jr. continued his perfect career, but boy, was it a tough night. Maybe the toughest of his entire brilliant, unbeaten career.

Mayweather (46-0, 26 KOs) found himself in a serious dogfight, trying to fend off the super aggressive Marcos Maidana of Argentina and his wild overhand rights, but his accuracy was the difference in a majority decision victory to unify welterweight world titles on Saturday night before a sold-out crowd of 16,268 at the MGM Grand Garden Arena.

Typically, Mayweather fights are over early, when it is obvious that he is dominating his opponent and on his way to a wipeout decision win. But Maidana, a 12-to-1 underdog and given no chance by anyone other than his most ardent supporters -- one media poll was 46-0 in Mayweather's favor -- was in the fight all the way.

"This was a tough, competitive fight. This is what fans want to see," said Mayweather, who was hit by more punches than in any of his 38 fights tracked by CompuBox. "I want to give fans an exciting fight. Normally, I box and move. Tonight, I gave fans an exciting fight."

He sure did. For action, it might have been his most exciting fight, perhaps with the exception of a 2012 junior middleweight title bout against Miguel Cotto. It was so good and competitive that talk after the fight immediately turned to the possibility of a fall rematch.

"He put pressure on me and that's when I decided to fight differently," Mayweather said. "I stood there and fought him. He's a good fighter, I take nothing away from him."

For the fight, Mayweather landed 230 of 426 blows (54 percent) while the nonstop punching Maidana connected on 221 of 858 (26 percent). Maidana threw punches from all kinds of angles and forced Mayweather into the ropes time and again.

Judges Burt Clements (117-111) and Dave Moretti (116-112) both had it for Mayweather, while Michael Pernick had it 114-114, eliciting booing from the crowd, which was filled with Argentine fans supporting Maidana. ESPN.com also had it for Mayweather, 115-113.

Maidana (35-4, 31 KOs), who mauled and brawled the whole fight, thought he won, as did his chanting fans.