With the rowdy home crowd rooting on underdog Britain, U.S. men's water polo captain Tony Azevedo wanted to take care of business early.

He did just that.

Azevedo scored four goals -- three of them in the opening quarter -- and fellow four-time Olympian Ryan Bailey scored three more to lead the U.S. past Britain 13-7 on Thursday to remain undefeated at the London Olympics.

The win puts the Americans on top of Group B with six points, one ahead of gold medal-favorite Serbia with two preliminary stage matches to go.

The U.S., runner-up four years ago in Beijing, jumped out to a 7-0 lead early in the second quarter and cruised from there against an outclassed British team that only qualified for the tournament as the host nation.

"We definitely wanted to start this game off stronger because we saw their two previous games when they came out on fire in the first quarter, and once a team gets going and the crowd gets behind them, they start throwing up shots and everything starts going in," Azevedo said. "We wanted to play strong defense and make sure we got a lead at the beginning."

Azevedo took care of that, scoring two shots from distance and then converting a penalty past Britain goalkeeper Ed Scott to make it 3-0 four minutes into the game. After pushing the lead to 7-0, the U.S. let up a bit.

The American captain got plenty of help, with Bailey scoring three goals and Shea Buckner adding two more.

"Tonight we kind of settled in and kind of let off the gas a little bit after going up," U.S. coach Terry Schroeder said. "But I think we're real happy. We're 3-0 for sure so it puts us in a good place in our bracket and sets up a good match with Serbia here in two days."

After Serbia, the U.S. wraps up the group stage against three-time defending champion Hungary on Monday. But for now, the focus is squarely on the Serbs, who drew with Montenegro in a bruising game earlier Thursday.

Bailey, who is listed at 6-6 and 245 pounds, is expecting the same sort of punishing play out of Serbia on Saturday.

"They're really a physical team, and so when somebody comes and tries to beat you up, you have to match their intensity and match their physical play," he said. "They're a great team with a lot of great players, so we're looking forward to it."

Against Montenegro, the Serbs let a two-goal lead slip away with two minutes to go, giving up goals to Aleksandar Ivovic and Mladan Janovic to draw 9-9 with their Balkan rivals.

"I'm totally exhausted," Serbia's Filip Filipovic said. "I think that we'll recover in two days and be able to give pressure to the American guys because we saw that they are in top form."

Serbia is in second in Group B, one point behind the U.S. Montenegro, meanwhile, is third with three points, but has its two weakest opponents to come -- Romania and Britain.

The intensity of the match stemmed from the countries shared history. Five players in the pool Thursday -- three from Montenegro and two from Serbia -- won silver as teammates for Serbia and Montenegro at the 2004 Olympics, two years before the countries separated.

In the final Group B match, Hungary recorded its first victory at the London Games, pulling away in the second half to beat Romania 17-15. The victory was a big one for the three-time defending Olympic champions, coming after losses in their first two matches at the games to Montenegro and Serbia.

"Finally," Hungary star Tamas Kasas said of the win, before qualifying that Hungary's defensive performance was "horrible."

Earlier Thursday in Group A, Spain earned an easy 13-9 win over Australia behind goals from 10 different players. Every outfield player except Balazs Sziranyi Somogyi scored for Spain, which is looking for its first Olympic medal in men's water polo since winning gold in 1996.

Spain has four points from three Group A matches, positioning it well for a spot in the quarterfinals, while Australia has just two points from three games.

Greece also improved its chances of reaching the knockout stage with its easy 11-4 win over Kazakhstan behind five goals from Ioannis Fountoulis. Greece has three points from three Group A games. Kazakhstan is winless and at the bottom of the group.

Also, Sandro Sukno and Miho Boskovic scored three goals each to lift unbeaten Croatia over Italy 11-6.