It Doesn’t Take a Genius: U.S. Must Win Big Tonight : Group A: In order to advance to the second round, Americans need to defeat Austria by at least three goals.

Asked Monday about his soccer team’s chances to advance to the World Cup’s second round, U.S. Coach Bob Gansler acted as though it gave him a headache to think about it. His subject when he taught at the University of Wisconsin Milwaukee was history, not math.

“The mathematical possibilities would require Einstein at his best,” Gansler said.

Without Einstein at their disposal, U.S. players turned to one of their own, defender Paul Krumpe of Redondo Beach, an aerospace engineering major at UCLA who quit his job at McDonnell Douglas to play for the national team.

Using a computer at the training camp here, Krumpe discovered a scenario involving six combinations of events and 18 teams that would enable the United States to become one of the 16 teams in the second round.

“It’s still within the realm of possibility, but it would be extremely difficult,” Gansler said.

So Gansler has spent the four days since a 1-0 loss to Italy in Rome preparing his team for the only variable it can control, a three-goal or better victory over Austria tonight in Florence.

Also winless after two games in the four-team Group A, the Austrians have an equally long wish list. It starts with a two-goal or better victory over the United States.

Soccer experts would say that Austria has a better chance of achieving its desired result than does the United States.

But soccer experts also said before the tournament that the Americans would score no goals in their three first-round games. It took them about an hour to prove the experts wrong on a goal by midfielder Paul Caligiuri in a 5-1 opening loss to Czechoslovakia.

That might not be much, but it is one more goal than has been scored by the Austrians.

With forwards Gerhard Rodax and Toni Polster, the second- and third-leading scorers in European professional leagues this season, Austria entered the World Cup with one of the most respected offenses.

But in 1-0 losses to Italy and Czechoslovakia, the midfielders had difficulty getting the ball to the forwards. That has resulted in frustration and dissension that might lead tonight to humiliation.

According to Monday’s Presse, a Vienna newspaper, the Austrians “are even starting to fear the much-mocked Americans.”

With speculation rampant in Austria that he will be fired if his team loses to the United States, Coach Josef Hickersberger has announced two midfield changes and added a third forward, Andreas Ogris.

Expecting an all-out assault from the Austrians at the beginning of the game, the U.S. players said they will employ the same nine-men-back defensive tactics that they used so effectively against Italy, but with more assertive counterattacks.

“Austria came to the World Cup with high expectations,” U.S. defender Desmond Armstrong said.

“If we hold together defensively, we can frustrate them and then get a counterattack going. If we score against them first, they might fold.”

Armstrong, who did not allow Italian striker Gianluca Vialli a shot Thursday night, draws Rodax, the No. 1 scorer in the Austrian League, for this game. Defender John Doyle of Fremont, Calif., has responsibility for the larger, less mobile Polster, the No. 2 scorer in the Spanish League.

“That makes you wonder about the Spanish League,” Armstrong said. “Polster only plays with his left foot.”

Naturally, Doyle is more concerned about Polster.

“He’s a proven scorer,” Doyle said. “Maradona hasn’t scored any goals here, but you know he’s a scorer. Polster will break out of this. I just hope he doesn’t do it against me.”

Gansler said the difference in his team from the first game to the second was its level of intensity. Based on practices this week, he said he believes the players will maintain the intensity they displayed against Italy.

But he felt it necessary to call a team meeting Sunday night because he was concerned the players might be distracted by questions about their future.

Six players--midfielders Tab Ramos of Hillside, N.J., John Harkes of Kearny, N.J., and Caligiuri of Santa Monica, forwards Peter Vermes of Delran, N.J., and Chris Sullivan of Redwood City, Calif. and Doyle--are in the preliminary stages of negotiating to play professionally in Europe.

The U.S. Soccer Federation is negotiating a deal for Ramos with Roda, a first-division team in the Netherlands. The player with the best prospects, however, might be Caligiuri, who has had contacts with two teams, Parma and Cagliari, in the Italian League.

“We’ve done a lot of talking about what guys are going to do after the World Cup,” said Vermes, who played for Volendam in the Dutch first division last season and is talking with teams in Switzerland, Belgium and the Netherlands.

“But it’s important that we do well as a team. We were all trying to do too much individually against Czechoslovakia. Maybe we had professional contracts on our minds.

“Against Italy, we realized that we’ll look good as individuals only if the team plays well. It’s important that we keep that in mind against Austria.”