The last time Sugar Ray Leonard set foot in a ring, Roberto Duran said, "No mas ," and Leonard became the WBC welterweight champion. Tonight, referee Arthur Mercante said, ""No mas " and stopped Leonard's title defense against Larry Bonds with 2:22 gone in the 10th round.

Later, when Leonard was asked the difference between Duran and Bonds, Bonds assumed the prerogative of a reply. "I am not a quitter," he said.

Leonard won the TKO in front of 20,000 in the Carrier Dome. Bonds won a moral victory; the Fighting Garbage Man from Denver is not trash. "Everyone here owes an apology to Larry Bonds," Leonard said later. t"He proved he was a legitimate contender. Now everyone understands why a man like Larry Bonds has trouble getting fights."

Leonard, who had predicted a knockout in 10 rounds or less, dominated from the prefight glares on. Although he knocked Bonds down at the end of the fourth round, and his left job continually made its mark, Leonard was unable to knock out the southpaw who had not fought since April 1980. And so, when the TKO was announced the crowd booed. "I couldn't kayo this man," Leonard said. "They don't see enough blood, so they booed."

Before the fight was stopped, judge Carol Castallano had given two rounds to Bonds, Vincent Rainone had called one round even and Harold Lederman had given all nine to Leonard.

At the beginning of the 10th round, Bonds, a man with a sly and deprecating wit, came out of his corner feigning a Leonard-inspired bolo punch. It was the worst move he made all night.

Leonard had had enough. He backed Bonds against the ropes, as he had throughout the fight, connecting with a flurry of five punches, several of them penetrating rights. Bonds sank to his knees. Mercante counted to eight and the fight resumed. But so did Leonard, pummeling Bonds with another flurry of lefts and rights, until Mercante said enough was enough.

After Leonard had left with his gaudy, green championship belt snugly around his midriff, Bonds' handlers paraded him around the ring on their shoulders, his fists held high in the air, as the crowd cheered.

Carl King, son of Don, and one of Bonds' managers said: "You heard the response of the crowd. They stopped it too quick. We weren't hurt."

Well, certainly King wasn't. Bonds said he wasn't hurt, though his puffy face said otherwise. "I think the fight was stopped unjustly," he said.

Bonds, 29, who has never gone more than 12 rounds, said it was his strategy to rally in the late rounds. Certainly, no one was rallying in the early ones. Leonard, who will fight southpaw Ayub Kalule for the WBA junior middleweight championship in June, said the first five rounds were "a feeling out process.

"I was quite frustrated," he added, "mainly because I wasn't able to get set. In the early rounds, I had to be very cautious."

From the first bell on, Leonard pursued Bonds, stalking him flat-footed and unsmiling, and often backing him against the ropes. Near the end of the fourth round, Leonard backed Bonds into the neutral corner and sent him to the floor with a right uppercut. The crowd yelled: "He's ready, Ray." But Bonds wasn't.

As often as Leonard cornered him, Bonds moved away. The garbage man was the only one who did any dancing last night, inaugurating what might be called the "alley shuffle."

"I was catching him on the shoulders and arms," Bonds said. "He came right at me and didn't dance like I expected him to."

Nothing much was expected of Bonds, who is now 29-4. In his last press conference before the fight, Leonard had said: "Either way, I can't win. If you say he's a nobody and he gives me a good fight, then what are you going to print?"

Earlier in the week, Bonds, whose previous biggest payday was $1,500, was asked if the pressure of being in a title fight after not being in the ring for almost a year bothered him. "No," he said. "I'm in the alleys eight hours a day with people staring out the windows, looking to see if I'm going to throw their cans. Now that's pressure."

When the fight was over, and the pressure gone, he was asked if it was worth it. "It was damn worth it," he replied.