For 45 minutes, the Americans were sloppy and slow, looking very much like the inconsistent bunch whose road to Germany was marked by bumps and potholes.

Once they took the field for the second half, though, the Americans played with the confidence, creativity and touch around the goal that won them two World Cups and made them the world's dominant team for much of the last two decades.

"We believe we can win this tournament," Abby Wambach said.

Lauren Cheney, making her first start since March, and Rachel Buehler scored in an offensive burst as the Americans beat a young but scrappy North Korea 2-0 on Tuesday. The victory puts the Americans atop Group C going into Saturday's game against World Cup newcomer Colombia.

If the U.S. wins that game and Sweden beats or ties North Korea, the U.S. will be on to the quarterfinals. The Swedes defeated Colombia 1-0 on Tuesday in the other group match. The U.S. wraps up group play July 6 against Sweden.

"It's always easier going forward" with a win, U.S. coach Pia Sundhage said. "We're happy, two great goals."

For the North Koreans, it was yet another loss to the Americans. This was the fourth straight World Cup that the teams met in the group stage, and the U.S. has won all but one of the games. As the Americans celebrated on the field, delighting a crowd that was decidedly pro-American, the North Koreans stood just beyond midfield, watching.

Afterward, North Korean coach Kim Kwang Min blamed his team's failings in the second half on a June 8 lightning strike during training in Pyongyang that sent "more than five" players to the hospital. Goalkeeper Hong Myong Hui, four defenders and some of the midfielders were the players most affected, Kim said.

"The physicians actually said the players were not capable of playing in the tournament," he said through an interpreter. "They're not physically ready for this match, but they had a strong will."

The North Koreans didn't seem as if anything was amiss, nearly matching the Americans in possession (53 percent to 47 percent) and getting seven shots on goal. And the lightning strike seemed to catch everyone off-guard, with the FIFA media officer at the venue saying she had no knowledge of it until Kim's postgame news conference.

The Americans are the top-ranked team in the world, two-time defending Olympic champions, and have the best goalkeeper (Hope Solo) and one of the best strikers (Wambach) in the game. Yet for the last few months, all they've heard about are their shortcomings and inconsistency.

After going more than two years without a loss, the U.S. dropped three games in five months. The Americans were stunned in the semifinals of regional World Cup qualifying by Mexico, a team that had been 0-24-1 against its northern neighbor. The U.S. had to win a home-and-home playoff with Italy just to get to Germany.

The United States lost to Sweden in the Four Nations opener, though it did go on to win the tournament, and then was beaten by England for the first time since 1988.

All along, the Americans insisted they would be fine once the tournament started.

"It doesn't matter what happened in the past," Wambach said. "It's all about what's happening in this tournament, and that's what we're focused on."

In the first half, though, the Americans were less than impressive. They started the game strong, controlling the game with crisp passing and good speed. But the North Koreans gained confidence as the game went on, shutting down the U.S. attack in the midfield and repeatedly pushing forward in the closing minutes before halftime.

Kim Su Gyong took a shot from close range in the 34th minute, but Solo punched it away. Four minutes later, Song Jung Sun slid a shot right in front of the goal that Solo couldn't get close to. No other Americans were there to clear it away — but no other North Koreans were, either, and Ali Krieger finally booted the ball to safety.

"We couldn't get a rhythm and we were struggling a bit to connect passes," Buehler said.

Sundhage told her players at halftime to take the ball outside and make more use of the flanks. The difference — and improvement — was clear immediately.

In the first five minutes, Cheney took two shots that went straight into Hong's hands. Wambach took a sliding shot from the edge of the 6-yard box in the 51st minute, only to see the ball sail over the net.

Finally, in the 54th, Wambach dribbled quickly up the left flank and took a step as if to move inside, spinning a North Korean defender around. Wambach dribbled a few more steps before chipping in a perfect cross that Cheney nodded past Hong.

"I'm actually not a very good header," Cheney said. "I just knew I wanted to redirect it back to the same place it came from."

It was Cheney's 14th goal in her 40th appearance for the United States.

"I'm going to have to take some tips from her," Wambach joked. "That goal gave me so much more confidence going into the rest of the second half."

The rest of the Americans, too.

After back-and-forth possession in the first half, the Americans owned the ball the rest of the game and could easily have tacked on another two or three goals. Wambach hit the crossbar in the 65th and Amy Rodriguez put a shot wide in the 73rd before Buehler scored the insurance goal in the 76th minute on a thunderous strike with her right foot.

It was the second goal of the defender's career.

"It felt good out there," Cheney said. "This game is all about feelings, and this game was a great feeling."