REIMS, France -- For all the goals, celebrations and wins of the past two weeks, the World Cup in some ways began Monday for the United States with a mistake.

Not a cataclysmic error or a failure of character. Just a mistake.

But World Cups can turn on one mistake. This one, resulting in the U.S. allowing its first goal in 674 minutes, didn't. Not yet.

With the ball at her feet, the place where she has the best claim to being among the best goalkeepers in the world, Alyssa Naeher picked the wrong pass. With Spain already pressing the U.S. with vigor bordering on recklessness in the opening minutes of Monday's knockout game, Naeher played a short pass to defender Becky Sauerbrunn to begin a buildup.

She hesitated uncharacteristically before the pass, as if unsure which teammate to choose. It still might not have mattered, but Sauerbrunn's own hesitation receiving the pass allowed Spain's Lucia Garcia to steal the ball and find Jennifer Hermoso. With Naeher pulled out of her goal, Hermoso lofted a shot that rose over Naeher's hand and found the back of the net.

"I think I just tried to do a little bit too much," Naeher said of the goal. "Shouldn't have played that ball into a pressure pocket. Probably a smarter decision to just play it a little bit higher up the field. But things happen when you try to play. Unfortunate way to give up a goal, but I thought we responded well."

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That sequence in the ninth minute led to the first goal the U.S. conceded in the World Cup -- and the first time it was so much as tied at a score of more than 0-0 in the knockout rounds since 2011. It also wiped out the momentum the Americans thrive on. Two minutes earlier, Tobin Heath drew a penalty that Megan Rapinoe capitalized on.

"Obviously, with pressure like that, just need to get rid of it," Rapinoe said. "I think we all kind of came together like, 'It's fine, it's early.' Obviously, getting an early goal for us, those things are going to happen. ... Just stay in it and have each other's back. "We'll watch film, and they won't do that again in that exact same way."

The goalkeeper and the back line responded on this day by keeping a clean sheet the rest of the way. Busier than they were in any of the first three games, maybe all three games combined, the defensive effort after the equalizing goal gave the U.S. the breathing room it needed to pull out a 2-1 win and move forward in the tournament.

In the end, Spain pushed for one more tying goal. At one point, Naeher rose to get to a ball ahead of a Spanish player, then stayed on her feet through the end of the subsequent play only to fall the ground in a collision.

While otherwise praising Naeher before the World Cup, former U.S. goalkeeper Briana Scurry noted it's impossible to know how someone will react to major tournament adversity until they experience it. It didn't mean she thought Naeher couldn't. She just didn't know. Couldn't know.

The miscommunication or miscue between Naeher and Sauerbrunn could have been more costly. The U.S. never did control this game, even as it fought throughout for the upper hand.

The game could have gone to extra time. It could have gone to penalty kicks, like the 2016 Olympic quarterfinal against Sweden that derailed a U.S. effort. It could have unraveled.

But it didn't. And now Naeher has some of that experience, too.

"When you get out into the knockout rounds, it's always so much more pressure, so much more tense out there," Rapinoe said. "Everything matters, every play matters. Every sort of wave of the game is important. I think halfway through the second half, it was like we need to take this up a notch. Obviously, there's quite a few of us that have been there in these big games and sort of realize those moments. And that experience was really big for us tonight."

Whether or not the World Cup began for the U.S. on Monday, it didn't end.

All eyes turn to Paris

There will be plenty of time this week to hype a game that has already received its share of hype, a quarterfinal in Paris between the teams that entered the tournament as betting favorites.

And Rapinoe, for one, is ready for the fun. Even if she picked a different word.

"Hopefully, a complete spectacle," Rapinoe said. "Just an absolute media circus. I hope it's huge and crazy. That's what it should be. This is the best game, this is what everybody wanted. I think we want it, seems like they're up for it ... all the fans. Maybe it will be a pretty even split between the fans in the stadium. We've been traveling pretty deep in this World Cup.

"I hope it's just a total s---show circus. It's going to be totally awesome. I think this is what everybody wants."

VAR smiles on the United States

It wasn't the first VAR review for the U.S. in this tournament, or even the first to involve a penalty kick, but it was the most important for the defending champion. And fittingly for this World Cup, it will leave its own trail of controversy. With extra time looming and the U.S. still short on quality scoring chances in the second half, Hungarian referee Katalin Kulcsar awarded a penalty when Rose Lavelle was clipped as she chased a ball across the box in the 71st minute. Replays showed minimal contact, albeit contact nonetheless, by the Spanish defender after Lavelle reached the ball.

After Spanish players gathered around the ball in a delaying tactic that was likely unnecessary given the frequency of VAR reviews in this World Cup, Kulcsar jogged over to the sideline, watched the review and held her ground on a penalty as the correct decision.

Alex Morgan stepped up to take the initial penalty, but Rapinoe said she was instructed during the delay to stick to the team's established protocol and take the penalty herself.

"It's ultimately the coach's decision, so the ball went back to Pinoe," Morgan said. "I'm happy taking it, I'm happy giving it to Pinoe."

The physical price of success

On a hot day, with temperatures at about 90 degrees at kickoff, and with the U.S. on three fewer days of rest than its opponent, Monday's game was always going to be a physical challenge for the Americans.

Spain then pressed and pressed on that pressure point, looking almost like North American rival Canada in its willingness to go in hard on every challenge. It was a style of play Kulcsar allowed from the outset, but she was consistent in allowing it. Everyone on the field for the U.S. seemed to take their share of the hits, but Morgan was perhaps the most frequent recipient.

"I got a knock last game, but luckily I recovered," Morgan said. "Maybe the Spain players saw that and wanted to be a little more aggressive with me. But I feel like, if anything, it took them off their game more than it took me off mine."

Just as in the game between the teams in January, Spain showed off the possession game for which it is known, nearly equaling the U.S. with possessing the ball 46% of time. But the physical play was a new twist that reflected a World Cup knockout game instead of a winter friendly.

"I don't remember that being this physical, this aggressive, this reckless -- in challenges at least," Morgan said. "For me, that was a little different. I wasn't expecting that. At the same time, we were able to capitalize on that with penalties."

Spain is coming

The contrast was stark between the challenges France and the United States faced in this round. France held off one final push from Marta, Christiane and Formiga, the stalwarts of a Brazilian team that has tantalized with its potential for more than a decade. It isn't clear what Brazil will look like when next on this stage.

The team the U.S. faced Monday is just getting started. Whether it was reckless or courageous, or maybe a little of both, Spain brought showed a fearlessness few opponents exhibit against the Americans. All the more from a team that has just one all-time World Cup win and had played the United States just once in its history.

Spain wasn't intimidated by the opponent or the stage. It is already well on its way to building the kind of talent pool that will allow it to win these games soon enough.

Her eye puffy from a first-half collision that resulted in her coming out of the game, Vicky Losada chose to focus more on what's ahead than the penalties that doomed her team Monday.

"I think we have a really good future," Losada said.