Most sports fans see the Sugar Ray Leonard-Roberto Duran bout as a classic confrontation between two evenly matched fighters. But the nation's gamblers have a different opinion. They are betting the event as if it is a mismatch.

In both Washington and Las Vegas yesterday, Leonard was listed as the 9-11 favorite. For the uninitiated, this type of odds quotation is the same as is used for baseball. It means if you like Leonard, you risk $11 to win $5. If you like Duran, you put up $5 to win $9.

Support for Leonard has grown since he was initially established as a 7-9 favorite, and the present odds -- by ordinary betting standards -- are very lopsided. By contrast, there were odds quotations on 13 major-league games yesterday, and none was as high as 9-11.

The prohibitive price has dampended the ardor of some of Leonard's fans and some local bookies report that they have received surprisingly little action on the fight for that reason. In Vegas, however, bookmakers are offering a vertiable cornucopia of wagering opportunities that enable a gambler to bet on virtually any opinion concerning the fight.

If you like Leonard to win by a knockout, you must lay only 7 to 5. If you like Duran by a knockout, you can get 11 to 5.If you think the fight will end in a draw, you can get 40-to-1 odds.

One casino is taking bets that the fight will end by a knockout in any particular round. The odds against a first-round knockout are 25 to 1; in the sixth round the price is only 5 to 1.

In such matters I turn for guidance to a man I'll call Harry, who is the best sports handicapper I know. I have quoted his usually brilliant opinions on football in this space before, but Harry's real specialty is boxing. I made the one serious fight wager of my life when Harry told me that Larry Holmes was a cinch to upset Ken Norton. He was, of course, right. And now he is talking in the same positive terms about Leonard.

The key to the fight, he says, is weight: Duran's move from the lightweight to the welterweight division.

"This is not as if he were 21 to 22 years old and grew naturally into a welterweight, as Leonard did," Harry said. "Duran is 29, and he's put that extra weight on a 5-foot-7 frame, and I don't see him being in the same shape as he used to be. The guys he's hitting now are 12 pounds heavier than the guys he was hitting as a lightweight, and they're not falling as easily for him.

"On Friday," Harry predicted, "I wouldn't be surprised if Leonard gets dropped early. He's cocky, and he may catch one of those short right hands after holding his left to low. But that'll bring out the best in him. I think he'll block punches with his right hand and keep jabbing Duran. In one fight last year Duran got his eye cut pretty bad by a guy who landed enough jabs.

"Somewhere along the line Leonard is going to cut him. I think he'll knock him out about the ninth round."

I related Harry's reasoning to my other personal guru in these matters, the former Ozone Park Assassin, Clem Florio.

He disputed the premise that Duran is carrying an "unnatural" amount of weight, and said plenty of other fighters have made a transition to a higher weight division at Duran's age.

Florio argued that Duran has not been impressive in his welterweight fights because he hasn't been in optimal shape. But he has trained hard for this fight and he is in shape now. Florio still gives a slight edge to Leonard, but he said, "Anybody who thinks Sugar Ray is a cinch is a fool. This fight ought to be 6 to 5, pick 'em."

That seems a bit more reasonble an assessment than the prevailing odds. There have to be better ways to make money than to lay 11 to 5 against a fighter who has won 69 out of 70 bouts in his career.