The U.S. celebrate the lone goal of their final group play match. Reuters

The U.S women's soccer team were expected to route North Korea, but settled for a 1-0 victory instead in front of 29,522 spectators at Old Trafford in Manchester, England, on Tuesday.

Abby Wambach scored in the 25th as the Americans finished group play undefeated. The U.S. were dominate in their other two outings, but managed only one goal against a North Korea squad that struggled at the London Games. Forward Alex Morgan was credited with the assist, after accepting a long ball from Lauren Cheney.

It was the 141th goal for Wambach, who remains one of the world's best strikers at age 32. Morgan and Wambach both hit the right post in the first half.

North Korean goalkeeper O Chang-ran was under pressure for most of the match, but did a solid job of holding off perhaps the most potent attack in the world.

More was expected out of the American squad going into the match. The U.S. defeated France, 4-2, and Colombia, 3-0, in their previous matches, while North Korea lost their last match, 5-0, to France.

The U.S. remains a potent force in the London Games, as the squad attempts to make up for the second-place finish in the 2011 World Cup. The Americans have scored eight unanswered goals, and goalkeeper Hope Solo hasn't conceded a goal in 256 minutes.

The squad appears confident heading into the knockout rounds.

''Do you see the way our team is performing?'' Solo said. ''We're having fun. We're scoring goals. We swept our group. I don't think there's any distractions.''

The U.S. faces New Zealand in the quarterfinals on Aug. 3.