LONDON >> When the game got tight, the experienced U.S. men’s water polo team didn’t.

Peter Varellas scored three times, goalkeeper Merrill Moses made big saves and captain Tony Azevedo netted a crucial late goal as the Americans held off Montenegro 8-7 to win their opening match at the London Olympics.

“We knew it was going to be a tough game,” said Moses, who had 11 stops on the night. “At halftime we said, ‘This game is not over.’ (After) the third quarter we said, ‘This game is not over, keep going.’ That’s what this veteran team is all about. We’ve been in all these situations before, we’re prepared for it and we executed well.”

Azevedo, who struggled much of the evening to crack a solid Montenegrin defense, scored from distance with less than a minute to play to put the Americans ahead 8-6. Vladimir Gojkovic answered 10 seconds later to pull Montenegro back within a goal.

The Montenegrins then had possession with 17 seconds to play but couldn’t get off a shot before time expired.

The victory puts the U.S. at the top of Group B along with Romania and gold medal-favorite Serbia. Sunday’s win against Montenegro — the 2012 European Championship silver medalists — provides a big boost to the U.S. in a brutal preliminary group that also includes three-time defending champion Hungary.

The United States hasn’t won gold in water polo since the 1904 St. Louis Olympics. The Americans have finished second three times — in 1984 in Los Angeles, in Seoul, South Korea, four years later, and at the 2008 Beijing Games.

The bulk of that 2008 team — 10 of the 13 players — is back this year in London. But the Americans’ experience is deeper than just Beijing. Four players are appearing in their third Olympics, and two — Azevedo and Ryan Bailey — are competing in their fourth.

The U.S. is hoping that all that time together in the pool — and the seven months the team spent training for the London Games — will make the difference this year between silver and gold.

In a hard-fought match against Montenegro, it appeared to do just that.

With chants of “USA, USA” from the packed crowd at the water polo arena, Varellas put the U.S. up 7-5 in the third quarter with a left-handed shot just inside the post. Montenegro rallied back with a goal from Aleksandar Ivovic — his third on the night — but the Americans didn’t panic despite losing the momentum.

Instead, Azevedo found an opening with 57 seconds to play and scored from way out to give the U.S. the two-goal cushion before the defense closed down Montenegro’s last-gasp effort.

“We went up on them early and kind of let them back into it, made it a little closer in the end than we would have hoped,” Varellas said. “Going up two goals under a minute you should be pretty comfortable. We let them get that quick goal, maybe a mental lapse, but we were able to finish in the end which is what matters most.”

The U.S. plays Romania, which beat Britain 13-4 earlier Sunday, in their next match on Tuesday.

Earlier in Group B, Serbia handed Hungary its first loss in men’s Olympic water polo in 12 years, beating the three-time defending champions 14-10.

Andrija Prlainovic scored five times to lead a relentless Serbian attack, while in the back goalkeeper Slobodan Sporo made a string of big saves to deny the Hungarians.

Hungary came into the London Games riding a 17-match Olympic unbeaten streak dating back to the 2000 Sydney Games.

In Group A, Croatia used a late surge to pull away for an 8-6 win over Greece, Spain scored an easy 14-6 victory over Kazakhstan behind five goals from Filipe Perrone Rocha, and Alex Giorgetti scored twice to lead 2011 world champion Italy past Australia 8-5.

The 12-team field is broken down into two groups of six for the preliminary stage, and the top four teams from each group advance to the knockout round.