Sometimes, a win is both deserved and lucky.

That was certainly true of the one the United States claimed in the Women's World Cup semifinal against Germany in Montreal on Tuesday. The 2-0 win was deserved. The 2-0 win was lucky.

The Americans shook off their sluggishness at last – and not a game too soon – as they faced the slightly favored Germans, the only other nation in the world to have claimed the title twice. Right off the bat, the U.S. dominated with aggression, movement and speed – all so conspicuously absent in its previous five games – and threatened with four big chances in the first half. The Germans seemed in a daze.

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In the second act, Germany, the tournament's highest-scoring team (20 goals in five games), looked more composed and dangerous early before the Yanks regained the upper hand. In that sense, the win was deserved.

But, ultimately, the game pivoted on a pair of dubious calls and a missed penalty.

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After German goalkeeper Nadine Angerer had denied Julie Johnston and Alex Morgan with point-blank saves early on, Johnston gave up a penalty just before the hour mark. With Alexandra Popp through into the American box, the young American defender laid an arm on the attacker, who readily went down on the contact.

Referee Teodora Albon from Romania awarded a penalty – and rightly so – but spared Johnston, who has otherwise been a rock for the U.S., a red card. By the letter of the law, Johnston denied Popp a goal-scoring opportunity and should have been sent off. She wasn't. And the game remained 11 vs. 11. That was lucky.

Goalkeeper Hope Solo – who has conceded just one goal this tournament, with a good deal of help from her virtually impenetrable back line – stalled penalty-taker Celia Sasic as long as she could, by her own admission. She then dove to her left; Sasic rolled the ball wide of the other post, missing Germany's chance to seize the momentum.

That was lucky, too.

On one of the subsequent plays, Anja Mittag whipped her shot just wide of Solo's goal. Then, right after Morgan pulled a shot across goal from a tough angle, she charged into the penalty area, where Annike Krahn blocked her with her back, sending the American striker crashing to the turf. Albon once again awarded a penalty, even though replays showed that the infraction probably took place outside of the box – but it was ever so close.

More luck.

"It was clearly outside of the goal area," German head coach Silvia Neid would tell reporters after the game. "And it can be seen quite clearly on television."

Carli Lloyd converted coolly, and the Americans had all the goals they needed.

All the same, Lloyd would wriggle her way into the box late in the game, twist to the back line and cut back a pass for Kelley O'Hara, who had never scored for her country in 61 previous appearances. The winger leaped and karate-kicked the hip-high cross into the net.

That part wasn't lucky. Lloyd's re-emergence from her own crisis in form to finally put the U.S. team on her back in consecutive games wasn't either. Nor was O'Hara's determined cross-field run to meet her pass.

There are plenty of expressions and clichés to be pulled out here about luck being the residue of hard work and preparation and all of that, and they'd probably all apply. But the point is that if a few bounces and calls broke the right way for the Americans, they had certainly positioned themselves to capitalize on them.

For perhaps the first time in this tournament, the tactics and game plan were absolutely spot-on, fitting the USA's strengths, exploiting its opponents' weaknesses and suiting its needs for this game.

Moving, at length, away from the 4-4-2 formation, and bringing in a third central midfielder to neutralize Germany in the center of the park worked. Keeping wingers Megan Rapinoe and Tobin Heath as far wide as possible, cutting inside only for backs Meghan Klingenberg and Ali Krieger to overlap, stretched Germany out. Morgan's speed and toil up front elongated the field. An early and eager push forward applied immediate pressure on a team that had demonstrated in the quarterfinals with France to be ill-equipped for starting a game on the back foot.

None of that was lucky. That was by design. And then it was execution.

Another cliché: it's better to be lucky than good.

On Tuesday, the Americans were both.

Leander Schaerlaeckens is a soccer columnist for Yahoo Sports. Follow him on Twitter @LeanderAlphabet.