Four months ago, he was just another skinny kid with fast hands who wanted to be the next Sugar Ray Leonard. There was a long line of 18-year-olds just like him at the National Amateur Boxing Championships in Charlotte, N.C., but none of them could fill a square ring like Floyd Favors.

"All of a sudden everybody was watching him; he was just so classy," said Joe Clough, an Olympic boxing coach who witnessed that show-stopping first act in the Floyd Favors story last April.

The second act was even better. One month after winning the national bantamweight title at Charlotte, the Capitol Heights, Md., boxer flew to Munich and beat the best 119-pounders in the world. "He went from being not even rated to No. 1 in the world. That just doesn't happen," Clough said.

Tuesday night Favors won another gold medal, at the National Sports Festival. This one was no surprise. And Favors, who graduated this year from Suitland High School, handled the pomp and circumstances of the occasion like a seasoned pro.

"The crowd here wanted to see more slugging," said Favors, who was booed in the third round for dancing away from his opponent, Herb Bivalacqua of Louisiana, after building up a big lead. "But I'm here to win. They want to see me charge in and slug it out. But if I end up on my back they won't be cheering for me."

If Favors did not please everyone in the audience, he lost no points with the men who run America's amateur boxing program. Favors is one of the two best prospects for Olympic gold in 1984, and after the boycott in 1980, those medals look particularly bright.

"He's not only a good boxer, he's a kid who can keep it all together," said Bob Surkein, the former national chairman of the American Boxing Federation and one of the organizers of the sport at the Festival. "I'd bet my right arm he's a medal winner if we can only keep him with us."

Surkein fears that Favors and the best of the amateurs will yield to the lure of professional boxing before the Olympics. What has made that fear reasonable is the new market for professional boxing created by cable television. There is good money and good exposure to be had for boxers who are no better than good.

Favors says not to worry. He doesn't plan on cashing in until after he has beaten Russians and won the heart of America in the '84 Olympics.

He already has a script for his movie. It begins with him sitting in a backyard in Capitol Heights with his dogs, watching a few neighborhood burnouts drinking in an alley. "Something clicked. I said to myself boxing is going to take me out of here."

The next scene shows Favors in a cramped gymnasium in Washington, sparring while his coach, William Dunlap, tells him he'll never make the grade. "He said, 'You don't have the heart to be a fighter.' "

The Cinderella part of the story comes next, beginning at the nationals and ending with a gold medal in 1984. After that Favors isn't quite sure what happens, but he's sure it will be taxing.

"I've been asking people like Sugar Ray how to handle the pressure of becoming a popular star," Favors said.

There wasn't a boxer at this festival who does not dream Favors' dream. These are mostly youths 18 to 20 who began boxing during years made rich and glamorous by Muhammad Ali and Leonard. These boxers don't just expect to win world championships; they're working to make the cover of People magazine. And they know they have to do more than box to get there.

Favors is working on his diction and his nickname. The 5-foot-5 fighter still calls himself "Shorty" when he stands before his bathroom mirror for private pep talks, but he knows he needs something with more pizazz for the public. He has gone through "Bam Bam" and "Flashy." "Magic Man" was a possibility until he met Dennis Milton, an Olympic boxer who actually works as a street corner magician in Manhattan.

Favors has temporarily put the nickname problem aside. He knows he still has a lot of boxing to learn. Tuesday night, some of his rough spots showed, but they only made his moments of greatness seem better in contrast.

In the first round, Favors hit Bivalacqua with a left jab, a right-hand lead and an uppercut, all picture perfect, before he was hit himself. In the second round, Favors walked into a right hook that shook him. Already well ahead in points, he played it safe the third round by keeping out of range. Some in the crowd let Favors know they expected a full three rounds of fighting for their money.

"You can't let the crowd dictate your fight," said Favors, who then conceded he doesn't like to send fans away unhappy. "It's hard to be at the top. I'm just trying to stay there."