Whitaker Wins Undisputed Title in First : Boxing: He knocks out Nazario to become first true lightweight champion since Roberto Duran in the 1970s.

Pernell Whitaker became boxing’s first undisputed lightweight champion since the 1970s reign of Roberto Duran, winning in stunning fashion Saturday night by knocking out Puerto Rican Juan Nazario with one second left in the first round.

Before 5,500 in Caesars Tahoe’s outdoor arena, who paid from $50 to $300 to watch three of boxing’s most celebrated performers, Whitaker easily stole the show.

His dramatic knockout came after his stablemate, Meldrick Taylor, and Hector Camacho had cruised to two relatively dull decisions.

Whitaker, who already had the International Boxing Federation and World Boxing Council championships, thus added Nazario’s World Boxing Assn. title.

The 1984 Olympic gold medalist, fighting through swarms of insects attracted by the bright television lights, snapped Nazario’s head back with a right jab and immediately followed with a chopping left hand that caught Nazario flush on the jaw.

For a second, the Puerto Rican was frozen in his tracks. Then he fell forward to the canvas, where he stayed. And as quickly as that, Whitaker became boxing’s second reigning undisputed champion, along with heavyweight champion Buster Douglas.

From the opening bell, it seemed likely Nazario wouldn’t last long. He seemed fearful and was ducking punches before Whitaker threw them. And his head and body were wide open. Nazario came in with a 22-2 record (Whitaker is 23-1).

Whitaker seemed delighted with his third belt . . . and not having to go 12 rounds.

“I’m shocked that I could hit him that hard,” he said.

“People said I couldn’t hit hard, that I had no power. The knockout punch was set up by the jab. I established it right away. I owe a lot to my strength coach, Bob Wareing. I’ve bulked up and added power.”

The left-handed Whitaker hits not with crushing power, but rather with a stinging effect thatas been toppling world-class opponents since his amateur days, before the Los Angeles Olympics.

Whitaker, who wants to fight the winner of the Sept. 22 Jorge Paez-Tony Lopez fight, might have generated the most excitement Saturday night, but he didn’t fight for the biggest purse.

He earned $500,000 for 2 minutes 59 seconds of work. Camacho earned $1 million for his carefully crafted effort against Tony Baltazar of Scottsdale, Ariz. Camacho, from Miami, is 39-0 and talked boldly of a fight with Julio Cesar Chavez next year.

Taylor, in his first bout since his loss in the last two seconds to Chavez March 17, earned $250,000 with a 10-round unanimous decision over Primo Ramos of Albuquerque, N.M.

There was some interest in Taylor Saturday, because his fight with Chavez was a brutal one, and he had taken considerable punishment in the closing rounds. He had had trouble making light-welterweight (140 pounds), and this one was at a more comfortable 144.

Ramos (39-7-1), who had lost a decision to Taylor (25-1-1) in 1987, simply was outmatched by Taylor’s athleticism.

The hard-hitting Taylor learned early that he probably wouldn’t knock out Ramos, and in fact seemed at times in danger of getting caught with some of Ramos’s wild punches.

There was a flaw in Taylor’s defense--he was caught repeatedly by Ramos’ short right hands and left hooks at close range--and at the midway point of the fight seemed to have embarked on the low-risk route.

After the Taylor and Camacho fights, many wondered if the money available to fighters today is dulling their bouts.

With multi-million-dollar pay-per-view opportunities down the road for both Taylor (a rematch with Chavez at 147 pounds, for example) and Camacho (who also wants to fight Chavez), both Taylor and Camacho took the safe route to decision victories.

Taylor even acknowledged that afterward. So did his trainer, George Benton.

“I could see early I wasn’t going to KO him, that he was very dangerous,” Taylor said. I was cautious, absolutely. I knew this guy was still coming after me. I didn’t want to get into any wild combinations and get caught with something.”

Said Benton: “I just wanted him to get used to moving around and boxing, to take his time. The other guy was a brawler, and I didn’t want him to get into a fight. Remember, he (Taylor) just came off a hard fight (against Chavez).”

Taylor, who was knocked down by a low blow in the seventh round, pulled away from Ramos in the ninth round. Taylor, who won by scores of 97-92 (twice) and 98-91, got caught inside by a right uppercut. But the punch seemed to hurt Ramos more than Taylor.

Ramos immediately went into a tailspin and was driven into the ropes by the former junior-welterweight champion. The ninth was a big one for Taylor, putting him into command for the first time in the fight.

For the powerfully built, usually hard-hitting Taylor to take the safe route to a decision is unusual. But for Camacho, it’s business as usual. He is quick afoot, keeps foes at bay with an outstanding right jab, lands left uppercuts and hooks often enough to win easy decisions, gets booed . . . and wins.

Baltazar, who fell to 35-4-1, pursued Camacho relentlessly, but his vaunted left hook was never a factor. But Baltazar’s boxing comeback, as well as his comeback in life, continues.

He served 2 1/2 years in prison, from 1986-88, after an auto accident in which two were killed. Once a highly regarded prospect, Baltazar seemed to lack sufficient timing Saturday to contend with one of the sport’s quickest athletes. Camacho, fighting in an ensemble that could be described as Indian curio shop, won on cards showing 118-109 (twice) and 117-110. At stake was his relatively meaningless junior-welterweight title from one of boxing’s fringe governing bodies, the World Boxing Organization.

But Camacho was by no means out of the woods until the closing rounds. Baltazar, on most cards, won several of the middle rounds, and Camacho had only a three-point lead on The Times’ card after nine.

But Camacho, who was existing all week on a diet drink to make 140, turned up the pace in the last three rounds and won going away.