"It all boils down to character," says United States Coach Walt Chyzowych, explaining how his undefeated team defeated Honduras Friday night at RFK Stadium to move into tonight's final of the World Youth Soccer Qualifying Championship against undefeated Mexico at Giants Stadium in New Jersey.

"Whenever you have to deal with mental character, the Americans are the best," Chyzowych said.

The U.S. team's poise -- especially from goalkeeper Craig Scarpelli -- seemed unusual for a group of 19-year-old schoolboys. And because of its victory over Honduras the U.S. team has been rewarded with a trip to Australia to compete (along with Mexico) for the Junior World Cup Soccer Championship in 1981.

The U.S. and Honduras had dueled to a scoreless tie after 80 minutes of regulation and a 1-1 deadlock after 20 minutes of overtime. So they engaged in a penalty kick shootout to determine the winner. After the round of five kicks, the teams were still tied, 5-5. (Each goal from the 12-Yard penalty kicks is added to the final score.)

So they went into a round of alternating single kicks, meaning if one team scored and other didn't, the game was over.

A frenzied crowd of 4,703 chanted "U-S-A . . . U-S-A" and waved dozens of American flags. Kevin Fouser responded by scoring into the left corner of the Honduras net.

When Honduran defender Jose Contreras' right-footed kick bounced off the crossbar back out to midfield, a wild mob scene ensued.

" just had a feeling of elation when I saw that ball hit the bar," said Chyzowych. "To go through this type of torture all night and then to see that . . ."

The U.S. will move to the qualifying final for the first time. Their best previous showing was in 1976 when they took third place by winning a consolation game in San Juan, P.R.

U.S. Soccer Federation officials feel their performance in this tournament, billed as the "most important soccer endeavor ever undertaken in America," will go long way to making soccer more popular in the U.S. It may also help bring World Cup games to the country in the next decade.

The immediate hero Friday was Fouser, a 19-year-old Atlanta native who said, "Scoring the winning goal felt really good, especially since I had such a terrible game. I just couldn't settle down and get my game together. I hope I redeemed myself."

But the hero for this entire qualifying tournament has to be keeper Scarpelli, who along with Mexico forward Alphonso Rodriquez, was named co-player of the semifinal round of the tournament which began with 18 teams.

Sarpelli, a slender 18-year-old from New Jersey, fought off Honduran blasts and squib kicks with dives, leaps, lunges and kicks after uncanny anticipation. High-scoring Honduras forward Jorge Montenegro dropped to his knees and buried his face in his hands after Scarpelli turned away a point-blank kick toward the corner.

The embattled keeper stopped 11 shots in all, four more than he had faced in the previous four games he was in the U.S. goal -- three of them shutouts.

"Pretty tough shots they had," Scarpelli and "I'd say this is the toughest game I've ever played in. I know one thing, that crowd sure picked me up after regulation play."

When asked through an interpreter how he thought Scarpelli performed, Montenegro looked toward the sky and said, "Magnifico."

It looked like all Scarpelli's efforts would go to waste when Honduras tied the game with only four minutes left in the second 10-minute overtime. If the American defense has a weakness (it has allowed only three regulation goals in six games) it is lack of concentration once it takes the lead.

"It was my fault," said captain and sweeperback Bill McKeon, quick to take the blame. "I'm supposed to make sure everybody is marking a man and I missed an assignment."

Asked if he thought his team's run of luck and good performances had run out after the Honduras goal, Chyzowych said, "No, I never thought of losing this game. I really knew we were going to win. The players were competing the best they could."

"I never thought about losing either," said Scarpelli, "When I heard all those people going wild and looked up and saw them waving flags I couldn't believe it. It reminded me of the U.S. hockey team in the Winter Olympics."

Mexico defeated Canada in Friday night's first game, 4-3, also in overtime.

When asked what he thought about the game (a preliminary to the Diplomat-Cosmos contest) in which both teams advance, win or lose, Chyzwych replied smiling, "It's just one of those games, you know. Who gives a damn?" r