It had to be a strange sight for the US women's national team, watching the normally lethal finisher Alex Morgan miss chance after chance on Friday. The young striker has been as close to automatic in front of goal since her breakout turn at last summer's World Cup. Yet in Friday's Olympic quarterfinal against New Zealand, Morgan saw shots go wide that she normally buries with ease.

Morgan still found a way to do her part for the American offense, setting up an Abby Wambach goal with one of the best passes of this Olympic tournament, but it was the defensive effort of Morgan and her teammates that helped secure a place in the Olympic semifinals with a 2-0 victory over the Football Ferns.

This US team was supposed to be an unstoppable attacking force, while the American defense came into the tournament seen as the weak link. That hasn't quite played out since that dramatic opening 4-2 victory against France. In that match, which saw USA give up two early goals to fall behind 2-0, the French attack exposed the US offense and raised serious questions about whether the backline was championship caliber.

"When you get goals scored on you, especially in the way we did against France, you learn a lot," said Wambach. "You don't take things for granted. It might be the best blessing in disguise for us."

Since those early French goals, the US has put together a 346-minute shutout streak. On Friday, the American team, not just the back four, put on an impressive group defensive effort that pressed New Zealand at every turn and reduced the underdogs to a series of harmless long-range shots.

In fact, Friday's victory was arguably as complete a game as the Americans have put together. The team's passing was sharp, and their movement was good all over the field, both on offense and defense. Several missed chances kept the score tight and kept the USA in danger of potentially surrendering a late equalizer.

Even as New Zealand began to show life in the second half, and the American midfield began to tire, the USA back four stepped up time and again. Captain Christie Rampone and Rachel Buehler halted all threats that came down the middle, while Amy LePeilbet turned in another steady outing at right back. Plus, Kelly O'Hara was her usual solid self at left back.

It was a strange game for US starlet Morgan. While she did miss some easy chances, the rest of her game was excellent. She kept the New Zealand defense under constant pressure; her touch was generally outstanding and her vision and execution on the assist to Wambach was as good as you will ever see.

But there were still those missed chances, which served as a reminder of just how young Morgan still is. She is 23 and there will still be some growing pains. That said, she has continued to be one of the United States' best players throughout this tournament, and Friday's match should only serve to motivate her as the team prepares for the toughest games of the tournament.

As Morgan adjusts to her role as the focal point of the attack, we caught a glimpse of a player who has taken up Morgan's former role of dangerous forward off the bench: Sydney LeRoux. Leroux is the only new face on this USA squad, the lone player who wasn't on the 2011 World Cup team, and she showed why against New Zealand. Her combination of speed and power gave the Football Ferns trouble from the moment she first touched the ball, and her skillful finish in the 87th minute secured the USA's place in the semifinals.

Now, the Americans are prepared to face their toughest challenge since the opening win versus France. Whether it is Great Britain or Canada, the USA will be taking on a squad considerably tougher than the past three teams the Americans have shut out. Not to take anything away from the team's defensive performances, but Colombia, North Korea and New Zealand aren't exactly "Murderer's Row" on the attacking front.

Regardless of that fact, what the past three shutouts have done is help build confidence in a defense that needed it, and now the players, from the forwards all the way back to goalkeeper Hope Solo, are working as a team to make life tough for opposing offenses. That is a vital development for the USA because, as dangerous as the American attack is supposed to be, the United States will not lift the gold medal if the defense doesn't play well.

On Friday, as it has for three straight matches, the USA backline showed their worth. Now, that defense stands two wins away from the transformation as a perceived weak link to championship caliber unit.