LAS VEGAS - Floyd Mayweather Jr. proved to the world that he can outgun any fighter you'll pay him enough money to face, though he barely did it last night, outpointing an aggressive Oscar De La Hoya to win a split decision - and take De La Hoya's World Boxing Council junior middleweight title.

Mayweather, undefeated as a professional, is 38-0 with 24 knockouts. The 30-year-old said after the fight that he planned to retire from boxing.

"I don't have anything else to prove," he said. "I want to start spending more time with my children."

De La Hoya's record dropped to 38-5 (30 KOs).

In a fight that may turn out to be the highest-grossing boxing match in history when all the pay-per-view TV money is counted, Mayweather started slowly. De La Hoya asserted himself, moving forward early in the fight with two- and three-punch combinations, occasionally backing Mayweather to the ropes and landing head shots. Mayweather's acclaimed defense seemed permeable, and he appeared to be holding back, waiting for an opening.

Mayweather finally seemed to wake up toward the close of Round 5, landing two hard left-right combinations in the closing 30 seconds. His defense woke up, too, and in the sixth round, he was slipping more shots from De La Hoya's outbursts. But De La Hoya kept coming, pushing Mayweather back continuously with a stiff left jab, then coming in with two-fisted flurries.

In Rounds 9 and 10, Mayweather began scoring by finding angles for single rights and lefts, and he nailed De La Hoya with a hard left to end the 10th.

In the final round, they stayed mostly in center ring. Mayweather backed up De La Hoya with hard shots twice, though it was briefly, and De La Hoya continued to press forward. They ended the bout trading blows for the final 10 seconds and had to be separated by referee Kenny Bayless. There were no knockdowns in the fight.

Despite having moved up to 154 pounds for the first time in his career, Mayweather entered the ring nearly a 2-1 betting favorite. The cocky Mayweather also entered the ring wearing an oversized Mexican hat and the colors of the Mexican flag, in an apparent effort to taunt De La Hoya, a native of East Los Angeles whose heritage is Mexican.

Size was not a factor in the fight.

Judge Tom Kaczmarek scored it 115-113 for De La Hoya. Jerry Roth had it 115-113 and Chuck Giampa 116-112 for Mayweather.

It's the fifth weight division in which Mayweather - a 1996 Olympic bronze medalist - has won a title belt as a professional, after starting his career in 1996 as a 130-pound super featherweight. De La Hoya, who also turned professional at 130, after winning a gold medal in the 1992 Barcelona Olympics, has won belts in six divisions.

It's unclear whether De La Hoya, 34, after a 15-year career in the ring, will fight again. His ventures outside the ring have included real estate, apparel and television production, and his company Golden Boy Promotions put together and marketed last night's bout with a lavish marketing budget. Golden Boy, which has growing influence in the sport, said the sellout crowd of 16,700 at the MGM Grand brought in $19 million in ticket sales, and purchases of the $54.95 pay-per-view telecast were expected to surpass 1.5 million.

With this bout, De La Hoya is expected to beat the record of $545 million that Mike Tyson generated in pay-per-view boxing revenue. De La Hoya will make at least $25 million for the fight; Mayweather, $10 million or more.

Mayweather prevailed despite family turbulence in the days before the fight. The Grand Rapids, Mich., native was raised to be a fighter in a family known for clashes inside the ring and out. His father Floyd Sr., a former boxer, began training the young Floyd to become a boxer when he was just a toddler, but he was spending time in prison for drug sales when his son boxed in the Olympics and early in his professional career.

The younger Mayweather's uncle Roger became and remains his trainer, a situation causing friction for both of them with Floyd Sr.

The elder Floyd trained De La Hoya for eight fights through last year, but he ended up in no one's corner last night. Another boxing uncle, Jeff Mayweather, lost to a young De La Hoya in 1993.