By Joseph White
The Associated Press

THESSALONIKI, Greece - If the U.S. soccer team doesn't shake its case of Olympic nerves, Mia Hamm and company could be going home early.

Starting with today's quarterfinal against Japan, it's time for the Americans to rediscover the collective aggression that made them so dominant for so long.

"There are some times we've played pretty tight, and you see that," Hamm said Thursday. "People are nervous. People are anxious. People, for some reason, that day don't have the confidence that they did last week."

It's bizarre to hear players who so often have epitomized confidence suddenly describe their team as tentative, but that was the case in all three first-round games.

"There has been something missing," forward Abby Wambach said. "Whether it be a systematic change, whether it be a lineup change, whatever the reason is, we have to figure it out. We just can't sit here and say, 'We have to do this.'

"Maybe that's what we've been lacking, the ability to say, 'I'm not going to be afraid to fail.' "

The United States' biggest stars aren't to blame for the team's jitters. Hamm, Julie Foudy, Kristine Lilly and Joy Fawcett have played exceptionally.

That leaves the younger players, who may be feeling the pressure - of the Olympics or of wanting to send the veterans out as winners.

Although coach April Heinrichs has been criticized for limiting her players' freedom with an overly structured game plan, it's clear the coach wants to see more sparks on the field from now on.

"Our team is dissatisfied with the way we've played," she said, pounding her fist into her palm. "You don't want to beat yourself up, because we have advanced, but the good news is we think our best performance is in front of us, that we're hungry, that we've learned some lessons this year, and that we're primed for a good performance."

It won't be easy against Japan. The U.S. team used to have its way with the Japanese, winning 13 straight games.

The last three games, however, have ended in draws, including a 1-1 exhibition in May when the U.S. team had to rally for the tie.

"What we learned is a really good lesson," Heinrichs said. "What we learned is Japan is definitely on the rise."