Middleweight champion Bernard Hopkins, the rough-and-tough ex-con from Philadelphia, knocked out Oscar De La Hoya, boxing's "Golden Boy," with two wicked left hooks to De La Hoya's body and head about midway through the ninth round of their 12-round bout at MGM Grand Garden Arena on Saturday night.

Hopkins, 39, defended his IBF, WBA and WBC middleweight titles for an unprecedented 19th consecutive time and also won De La Hoya's lightly regarded WBO middleweight belt. De La Hoya (37-4, 29 knockouts) was knocked out for the first time in his 41-fight career, and was knocked down for only the fifth time. After the fight, De La Hoya refused to speculate about his future, but several of his handlers have indicated he'll fight once more before retiring.

After Hopkins (45-2-1, 32 knockouts) backed De La Hoya against the ropes, he landed the two powerful punches, first throwing a shot to De La Hoya's ribs and liver and then to the back of his head. De La Hoya, 31, grimaced, fell under the ropes and put both of his gloves to his head with 1 minute 38 seconds left in the round. Referee Kenny Bayless counted out De La Hoya, and then Hopkins did a somersault in the ring and jumped on a turnbuckle and raised his arms in the air.

"I hit him with the liver shot," Hopkins said. "When I threw the hook and hit him, I heard him say, 'Ahhh.' . . . It was a liver shot with Hopkins sauce on it."

Said De La Hoya: "It was a great shot. It was a great left hook. He hit me right on the button. I tried to get up, believe me."

The first eight rounds were fought closely. Judge Keith Macdonald had De La Hoya winning the bout after eight rounds, 77-75; the other two judges had Hopkins leading, 79-73 and 78-74. Macdonald had De La Hoya winning five of the first six rounds; Judge Dave Moretti had De La Hoya winning the second round, and judge Paul Smith had him winning the first and sixth.

Hopkins landed 99 punches, compared with De La Hoya's 82, and Hopkins landed 17 more power punches.

The two fighters, whose personalities and boxing styles are strikingly different, made contrasting entrances into the ring as well. De La Hoya, the ultra-popular Latin fighter, wore a black robe and black trunks and was led by a mariachi band. Hopkins, the outspoken and stoic fighter known as "The Executioner," walked to the ring to the sound of Frank Sinatra's "My Way," and two rappers shouted "The Champ Is Here" as he climbed through the ropes.

It didn't take long for much of the crowd of more than 16,100 fans to start chanting "Oscar! Oscar!" early in the opening round. Hopkins delivered the first big punch, a right hand to De La Hoya's head, but De La Hoya landed a powerful left hook to Hopkins's face in the final 15 seconds of the round.

After both fighters spent much of the first two rounds dancing and clenching, De La Hoya attacked Hopkins with a flurry of combinations and landed a left hook that seemed to surprise Hopkins just before the bell at the end of the second. De La Hoya, who was cautious of Hopkins's three-inch advantage in reach, was the aggressor early in the fight, but by the third and fourth rounds, neither fighter seemed willing to attack.

Hopkins caught De La Hoya lunging near the ropes at the end of the fifth round, went for the knockout but missed. In the sixth, Hopkins tried to land three straight jabs, but barely landed one of them. De La Hoya, fighting in the 160-pound ranks for only the second time, seemed to absorb Hopkins's punches early in the fight, but Hopkins's power started wearing down the six-time champion in the later rounds.

In the eighth, De La Hoya seemed to stun Hopkins with a strong left uppercut, but Hopkins came back with a strong left hook. Hopkins opened the ninth by landing a right uppercut and right hook, and De La Hoya was never able to recover.

Whether De La Hoya was going to be able to throw his left hook effectively was an issue before the fight. Only hours before the fight, De La Hoya's handlers disclosed he'd received 11 stitches between the middle and ring fingers of his left hand on Wednesday, after he was accidentally cut by scissors while one of his trainers removed tape following a workout. The V-shaped cut wasn't very deep, but De La Hoya's left hand was bandaged -- his trainers asked to use more gauze in his locker room before the fight, but judges were unwilling to allow it.

The hand was numbed with a local anesthetic on Wednesday night, and that injection led to questions as to whether traces of a numbing agent, nearly all of which are substances banned by the Nevada State Athletic Commission, would show up in De La Hoya's pre- and post-fight urine tests.

"If he did not take any further shots, the Lidocaine should have worn off by now," Mark Ratner, executive director of the Nevada State Athletic Commission, said before the fight. "If it shows up in the pre- or post-fight tests, then it would be considered a banned substance, and the Commission would act on it."

The Nevada State Athletic Commission suspended Fernando Vargas in 2002 for nine months and fined him $100,000 after he tested positive for an anabolic steroid following his knockout loss to De La Hoya.

The injury didn't seem to affect De La Hoya's ability to land his left hook, which was instrumental in him knocking down Ike Quartey and Vargas in two of the signature victories of his illustrious career.

De La Hoya, who was made an underdog for the first time in his 41-fight career, already faced big odds in beating Hopkins, whom Las Vegas oddsmakers made more than a 2-to-1 favorite. Hopkins hasn't lost since 1993, when Roy Jones Jr. won a narrow 12-round decision over him at RFK Stadium.

Saturday night's fight generated the attention that boxing has missed over the last several years because of its diluted heavyweight division. Not since Mike Tyson was knocking out opponents in a flash had boxing engendered as much excitement in Las Vegas. The 17,157-seat arena was sold out, with ringside seats selling for as much as $12,000. Actress Nicole Kidman, actor Billy Crystal, Sen. John McCain (R-Ariz.) and former NBA superstars Magic Johnson and Charles Barkley were all sitting ringside.

"It was a liver shot with Hopkins sauce on it," said Bernard Hopkins (45-2-1), above, of his decisive blow. "He hit me right on the button," De La Hoya said.