LOS ANGELES-The Battle of Los Angeles ended pretty much the way it began, with Oscar De La Hoya coming forward, shoulders hunched, chin down, waiting to find the KO punch that would never come.

In the three minutes that may go down to define two careers, it was Sugar Shane Mosley who wound up fighting the round De La Hoya needed to fight.

And once again, it was De La Hoya who was unable to close the show.

Fighting a brilliant tactical fight with occasional flashes of the kind of savagery that was supposed to belong to De La Hoya, Mosley pulled victory from the brink of defeat with a rousing 12th-round rally to earn a split-decision victory and De La Hoya’s welterweight title last night at the Staples Center.

Mosley’s victory was all the more impressive because he seemed finished at the halfway point, worn down by De La Hoya’s superior size and strength and spent from the desperation of his own efforts.

But as De La Hoya waned over the second half of the fight, Mosley rallied.

His transcendent 12th round – when Mosley fought with the controlled abandon of a fighter who believed himself to be behind on the cards – was not only the margin of victory, because he needed it to avoid the injustice of a draw.

It was also the clearest possible indication of the difference between the two men last night, and the most glaring example of that certain little something that has been missing from De La Hoya’s efforts over the past three years.

“It was a great fight,” Mosley (35-0) said. “We went toe-to-toe in the 12th round. We went soul searching.”

Once again, De La Hoya’s soul came up just a little barren.

Much of that was due to the difference in hand speed – Mosley is so fast his flurries remind one of the way a cheetah runs in the wild, so quickly that it can appear the image is strobing.

Unlike the final round of the Felix Trinidad fight, when De La Hoya was stuck in reverse gear, he finished up against Mosley going forward.

But he was not punching, because the speed of Mosley was making him think.

And wait. And hesitate.

And even when De La Hoya was able to stop his brain and start his fists, he found Mosley’s gloves in his face first.

The final punchstat numbers – 284 punches landed over the 12 rounds by Mosley to 257 by De La Hoya – were not nearly as indicative as a breakdown of the final round alone.

Over the last three minutes, Mosley outpunched De La Hoya, 88 to 72, and outlanded him by an astounding 45-18.

“I knew he was fast,” De La Hoya (32-2) said. “I matched his speed.”

Wrong. In a fight that began as if it would be decided by power, the final verdict was rendered by speed.

Lou Filippo (116-112) and Pat Russell (115-113) had Mosley ahead, Marty Sammon had De La Hoya (115-113). The Post had Mosley the winner, 115-113.

“De La Hoya is a great champion,” Mosley said. “I was just the better man tonight.”

At least, Mosley was the better man when it counted.

After a terrific first round, in which Mosley appeared to be the most complete welterweight since Sugar Ray Leonard, the man whose nickname he lifted, Mosley seemed to be steadily wearing down under the pressure of De La Hoya, who had the height advantage and the edge of having fought as a welterweight since 1997.

De La Hoya had an overpowering second round, a good third, and appeared to be in control of the fight after a sixth round that had Mosley looking tired and almost slow. At the halfway point, De La Hoya was up on two cards and even on the third.

But then, as in the fight against Trinidad, things began to go south for De La Hoya.

Mosley outboxed De La Hoya through a slow seventh and pulled out the eighth when, with a minute left in the round, he turned southpaw to snap several right jabs into De La Hoya’s face.

After that, De La Hoya did not clearly win another round until the 11th, but when he went back to his corner, his nose was bleeding slightly and his chest was heaving mightily.

The 12th round was “Oscar De La Hoya, This Is Your Life,” but try as he might, De La Hoya never came close to landing the punch he needed to turn the momentum back in his favor.

Indeed, it was De La Hoya who was closer to hitting the deck in the final round after Mosley landed a slamming right lead followed by a 1-2 and a right-left to the head that had De La Hoya awkwardly groping for support.

And when De La Hoya shook his head and smirked toward the crowd over Mosley’s shoulder, it removed any doubt that he had been hurt, and hurt badly.

De La Hoya survived that hurt, but now his career seems seriously damaged.

A loser now in two of his last three fights, De La Hoya shows a disturbing tendency to fade over the second half of a fight. And now, his devastating, fight-saving rally against Ike Quartey in the 12th round of their February 1999 battle looks like the exception, not the rule.

Plus, there is now strong evidence that punch for punch and skill for skill, Shane Mosley is simply the better fighter. They had done this for fun dozens of times as teenaged amateur rivals in various LA gyms.

Last night, they did it for real, for real money, and one of them emerged as a real winner.

It was not the one they call the Golden Boy, not the one who got the cheers entering the ring, not the one who got the lion’s share ($8 million to $4.5 million) of the purse.

Last night, the real lion was Shane Mosley.

“People got their money’s worth,” said De La Hoya. “There’s got to be a rematch. Every great fight deserves one.”

De La Hoya deserves one, too.

But how will it turn out any differently?