INDIANAPOLIS, AUG. 16 -- Arnaldo Mesa of Cuba pointed a finger at U.S. boxer Kelcie Banks and turned his thumb down. Banks pointed to himself and turned his thumb up. The ayes prevailed.

In the most stirring fight of the Pan American Games, world champion featherweight Banks shook off a devastating short left to the face that floored him with 27 seconds remaining in the first round today, and survived to assure himself at least a bronze medal. The Cubans did not agree, but the scorecard said Banks had overcome the first-round knockdown to receive a 3-2 decision over Mesa in their quarterfinal fight.

Banks, a self-proclaimed egotist from Chicago who says he has had more than 500 amateur fights (506-66), was the first American to get a decision over a member of the Cuban team, rated No. 1 in the world.

The Cuban team has had problems here out of the ring, most notably a brawl in which several Cuban boxers went into the stands Friday night to spar with anti-Castro protesters.

There were no disturbances today, save for the joyous one after Banks' victory, which was the kind of decision that could well turn the tide in the United States' favor for the rest of the tournament.

Cuban coach Alcides Sagarra thought Mesa had been the victim of a heist. Mesa held his arms out wide as if pleading to the U.S. corner. Banks shrugged philosophically and spoke, his favorite occupation besides boxing.

"He caught me with a good shot and shook me up, no doubt," Banks said. "But not as much as people think. I picked myself up, regained my poise and did what I had to do."

Banks was one of three U.S. boxers to advance at the Indianapolis Convention Center. Michael Carbajal had almost as difficult a time evading Colin Moore of Guyana before receiving a 5-0 decision to also clinch a bronze. He next meets Cuban world champion light flyweight Juan Torres Wednesday night in the semifinals.

In his first bout of the competition, Olympic Festival light welterweight champion Todd Foster had the easiest time of the Americans, stopping George Kellman of Antigua with a dire right hand at 1:13 of the second round.

Banks, with a reputation as one who uses his mouth almost as much as his fists, nearly didn't get to the semifinals. Banks and Mesa had met once previously, last year in a USA-Cuba dual match, with Banks winning on points, and that perhaps caused some overconfidence.

"A lot of things have been put on Kelcie as far as his glib tongue and his attitude," U.S. coach Roosevelt Sanders said. "But this proved to me he really wants to box. I believe in him wholly now."

It had been suggested by some that Banks could be heading for an early exit, and he indeed flirted with disaster in the first round, which three of five judges awarded to Mesa. But his artful resurgence in the last two rounds won it for him, and the five judges scored it a total of 294-289.

"I scored enough to win, no doubt," Banks said. "The knockdown was the only big factor for him."

A 6-footer to Mesa's 5 feet 5, Banks had a significant height and reach advantage. But he did not use it in the first round, preferring to close in and slug it out with the strong Cuban. It was not a wise choice.

The knockdown came as Banks pulled in close and prepared what he hoped would be a good right. But while Banks' mind meandered, Mesa countered. He set it up with a small right, then landed a short left to Banks' jaw and cheekbone. It was so short it was almost invisible, and the next thing the crowd knew, its world champion was prone on the canvas, taking an eight count as he got to his feet.

"I was sitting in one spot, waiting too long to throw," Banks said. "I deserved it. He caught me with a clean shot. But it wasn't a big deal. It only put him up by a point."

According to international rules, knockdown punches only count as one punch, worth a third of a point just like all the rest. That was what saved Banks. In the second round he was a smarter fighter, leading with his long right jab and keeping his left permanently cocked. He scored consistently the rest of the bout, winning the second round on three cards and the third on four. By the end, Mesa was literally racing away from the jabs, with Banks stalking.

Mesa and Sagarra said later they felt the fight should have been stopped when Banks went down. They said that he was allowed too much time to recover after the eight count by referee Alfredo La Madrid of Colombia, and that Mesa won on points anyway.

"Banks was KO'd," Sagarra said. "He got up completely staggering . . . We believe Mesa obtained enough points to win the fight . . . {Banks} was in very bad shape. This is amateur boxing, not professional. The only thing that bothers you is to lose when you haven't lost. When you lose and it's fair, it's no problem."

Mesa said the first round was his, the second close, and the third his again. He said he felt he had lost because the judges were influenced by a partisan crowd.

"I thought they'd stop it in the first round," he said. "In the second it was very close. In the third, there were a lot of punches but they didn't hit me."

Banks next meets Esteban Flores of Puerto Rico, who advanced earlier today with a unanimous decision over Billy Downey of Canada. They will fight in the semifinals Wednesday.

More important, the Banks-Mesa fight was just the first of a number of anticipated U.S.-Cuba matchups, and the victory gives the U.S. team great momentum going into Monday night when three more Americans are to meet Cubans in quarterfinal bouts and a fourth American also is scheduled to fight.

"We're still taking it one bout at a time," Sanders said. "I hope this bout put some fire in the guys as far as the Cuban mystique, and them being unbeatable. This says it can be done, and there's no reason why it shouldn't."

On Wednesday, light heavyweight Andrew Maynard of Cheverly, Md., will fight in one of the most closely watched bouts of the Games when he meets Cuban world champion Pablo Romero in what should be a bitterly contested semifinal. Romero was one of the Cubans who rushed into the stands Friday night, and was seen striking a spectator with right uppercuts.