If having fun in the ring is Sugar Ray Leonard's measure of success, he had the time of his life against an overmatched Donny Lalonde.

Leonard, showing flashes of power few thought he could bring against a light heavyweight champion, fought back from only the second knockdown of his 11-year pro career Monday night to knock Lalonde out in the ninth round and win two boxing titles."I was just out there to have some fun," Leonard said after returning from an 18-month ring absence to win for the 35th time in 36 fights. "I happen to be out there because I love being there, that's it."

Leonard, further cementing his already considerable place in boxing lore, became the first man in history to win parts of five titles while quieting critics who suggested he had had one comeback too many and had no business being in the ring.

He also diplayed at its best the fiery determination to win that, perhaps more than anything, has made him one of the era's greatest fighters.

"Ray dug a little deeper than I did," said Lalonde. "Ray's got a lot of heart, he's a great champion."

Leonard, fighting for only the third time in nearly seven years, battled back from a flash knockdown in the fourth round to turn the tables and become the power puncher against the hard-hitting Canadian.

Fighting flat-footed and refusing to back off, Leonard turned in a brilliant ninth-round performance, knocking Lalonde down once before stopping him at 2:30 of the round wih a vicious left hook followed by a right hand.

"It was just a matter of me keeping my composure and trying to get the left hook in there," Leonard said. "It was just a matter of time before I caught him."

The end wasn't always so clear-cut, however, in a fight that Lalonde was in all the way and was actually leading on one ringside judge's scorecard after eight rounds.

"I felt I was way ahead," Lalonde said. "I thought I had him hurt quite a few times."

Lalonde, whose chances of winning rested solely on landing his right hand to Leonard's head, did just that in the fourth round, catching Leonard flush on the face as Leonard attempted to throw a left hook.

Leonard had been down only once before in his career - against Kevin Howard in his first comeback fight - and he didn't stay down long this time.

Up at the count of three, Leonard appeared unhurt and actually was backing Lalonde up as the round drew to a close.

"I wasn't hurt at all," the 32-year-old Leonard said. "After I was knocked down it wasn't a matter of desperation, it was a matter of getting back respect from him."

Leonard came out to win that respect in the fifth round, landing two big rights to Lalonde's head early and several good left hooks in a big comeback that seemed to turn the tide of the fight.

"Ray got busy with his hands and I started loading up on the right," said Lalonde. "The worst thing I could do was wait for the right hand, and that's what I did."

Leonard, abandoning any pretense of movement, kept the pressure on in the next three rounds. By then, Lalonde's hands were down and Leonard was able to connect almost at will to the head of his taller opponent.

"He started falling asleep in the seventh round," Leonard said. "I knew it was only a matter of time."

But Lalonde refused to back off, and early in the ninth round caught Leonard with a

good right followed by several uppercuts on the ropes.

Leonard, though, was unhurt and backed off only briefly before attacking Lalonde with a savage flurry, landing 16 straight punches to the head before the Canadian fighter staggered off the ropes.

Leonard followed Lalonde off the ropes and hit him with a left hook that caught Lalonde flush on the right side of the face and put him down for the first time.

Lalonde got up, shook his head at Leonard as if to acknowledge the punch, and waited for referee Richard Steele to resume the action.

When he did, Leonard unleashed a left hook followed by a right hand that put Lalonde on his back under the ropes, where Steele counted him out. It was more than a minute before Lalonde moved from the position, while Leonard was celebrating across the ring.

"Ray can punch," Lalonde said. "Ray Leonard is just a better fighter, what can I say."

The impressive win gave Leonard the World Boxing Council light heavyweight title held by Lalonde and also the WBC's newly created super middleweight crown. It also touched off speculation about possible future fights for Leonard, perhaps a rematch with Thomas Hearns of their epic 1981 fight won by Leonard.

Leonard, though, said it was too early to make any decision about his future.

"I just want to take my time, evaluate the film, and make a rational decision," he said. "I'm going to go home and enjoy my family right now."

Leonard, who weighed in at 165 pounds Monday morning to 167 for Lalonde, also revealed he had cheated at the weigh-in.

Leonard said he put silver dollars in his jogging suit to make it appear to Lalonde that he weighed more.

"I had about 40-50 in each pocket," he said. "What I actually weighed this morning was 1591/2."

Leonard won't have to worry about paying for the silver dollars. He earned a reported $15 million to Lalonde's $5 million in a fight that attracted 13,246 fans to the 15,300 seat outdoor arena at Caesars Palace.

The live gate for the bout was $7.5 million and promoters claimed early figures showed some 800,000 households bought the pay-per-view broadcast at $29.95 apiece.