The Associated Press

PHILADELPHIA - There was a weakness in U.S. women's soccer, and coach April Heinrichs has been trying to cure it for years. It looks like she has, because the Americans have been sensational on set pieces in the World Cup.

Through two victories, the United States has scored six of its eight goals off either corner kicks, free kicks or penalty kicks. Mia Hamm, reaffirming herself as the best player in the game, has played a role in five of them: three assists on corners, one free-kick goal and one on a penalty kick.

"At this level," Hamm said, "it's very important to be strong on set pieces. It's something we've worked on."

Indeed, Heinrichs has paid special attention to it. The Americans already were as good as anyone in the run of action with their attacking, often creative style. But they were not as dangerous on plays emanating from stoppages.

"For the past few years, April has done a wonderful job of keeping our goals written down," forward Abby Wambach said, speaking of objectives, not the number of balls that go into the net. "She put it in ink and talked about what kind of percentage of success we want to have on set pieces.

"Even if we don't get a ton of goals in a game, we are being successful in the goals we set as important."

But they are getting a ton of goals, winning 3-1 and 5-0. Heading into today's game in Columbus against a shorter, less-experienced North Korea, more goals off set plays are a distinct possibility.

Heinrichs was beaming after Thursday's game when asked about the success off set pieces.

"This team's strength is heading and to score four goals off set pieces, that is a big achievement," she said. "We wanted battlers on the field against Nigeria - in the air, on the ground - and to have the ability to do well off set plays.

"We need to be powerful, fearless, aggressive and athletic."