For some, the hairline is starting to creep backward. There’s plenty of reason to smile most days, and plenty of facial creases when they do. The average age on the U.S. men’s water polo team is 30. Ten of the players were on the 2008 squad that won Olympic silver. Six were at the Athens Games, and two were around for the 2000 Games.

The U.S. squad will need to draw on that experience to rebound from its disappointing finish to group play Monday. The Americans opened the Olympics with a 3-0 start. They treated their early opponents like mere inconveniences standing between them and a return trip to the gold-medal game.

But a two-game slide, marked by uninspired defense, has put the Americans in an unfavorable position as the tournament moves to its quarterfinal round, where a date with the undefeated team from Croatia awaits. The loser goes home.

The United States dropped its past two games in frustrating fashion, first an 11-6 loss to Serbia Saturday, followed Monday by another lopsided 11-6 affair to Hungary, the squad that beat the Americans in the gold-medal game in Beijing.

The Americans’ ticket into the quarterfinal bracket was punched even before their two-game slide. Because they posted the fourth-best record in Group B play, they must face Croatia, the top Group A team, on Wednesday. Croatia is the lone team that has yet to lose a match.

“It’s a brand new tournament,” U.S. Coach Terry Schroeder said. “We’ve got to start fresh, we got to stay in the moment, we got to find a way to find our heart, and that means playing good defense.”

That would be a drastic departure from the past two matches, in which the Americans allowed their foes to move the ball to the center, kicking out at will. A team that entered the tournament hoping to hold each opponent to only six goals has allowed 22 in the past two games.

“I’m concerned, for sure,” Schroeder said. “I thought we’d come out ticked today after getting beat up pretty good by Serbia.”

The clock is, in fact, ticking on the U.S. team. With half the team age 30 and above, these Games could represent the last chance for a tight-knit nucleus to win Olympic gold, a feat the United States hasn’t managed since 1904.

Many U.S. players passed on posh contracts to play in Europe in order to train together and take aim at gold in London. Monday’s loss provided a gut-check of sorts for some.

“We’re all here because we love it,” said Tony Azevedo, the team captain. “You don’t make money. We play because we love it.”

Hungary scored the game’s first four goals and held the Americans scoreless for the first 12 minutes. Leading the way for Hungary was Norbert Hosnyanszky, who had three goals. No American managed more than one.

“It’s our defense that’s dictating our play,” Azevedo said. “For some reason, we’re not playing our defense.”

While Monday’s game was mostly about bracket positioning, a strong showing would have given the United States a boost. Hungary has won the past three Olympic gold medals in men’s water polo, and the Americans have beaten the talented squad only once in the past decade.

Players have a day to rest, study video and prepare to bounce back against Croatia.

“We knew the biggest game is the next opponent,” Azevedo said. “That’s the one that matters. We’ve known that from the start.”

Still, players concede that mentally, they need to find a reset button. And they have to do it now. Monday’s tough loss doesn’t have to affect them in the pool Wednesday, but it certainly could.

“It all matters how you click that day,” said goalkeeper Merrill Moses. “I don’t think that momentum is an issue.”