Tony Azevedo scored three goals Sunday and the United States held on for an 8-7 win over Montenegro to begin the Olympic water polo tournament. Coming off a silver-medal performance in Beijing, the first water polo medal for the American men in 20 years, they scored a significant victory over a country that has become a force in the sport. Azevedo scored his third goal with 57 seconds left in the game to give the United States an 8-6 lead. Vladimir Gojkovic tallied for Montenegro just 11 seconds later, but the Americans survived down the stretch. It was the last of six games played on the first day of the men\'s tournament with Serbia and Romania also posting victories in Group B, of which the United States is a member. Serbia, which defeated Montenegro for the bronze medal four years ago, knocked off defending gold medal winner Hungary 14-10. Romania slammed Britain 11-4. In Group A, Croatia edged Greece 8-6, Spain cruised by Kazakhstan 14-6 and Italy was an 8-5 winner over Australia. The United States will play next Tuesday against Romania.