DENVER -- The United States men's national team headed into Sunday's CONCACAF Nations League final against Mexico as a side heavy on potential but light on experience. Yet in an engrossing contest that lasted almost three hours, this young U.S. team grew before the collective eyes of those in attendance, prevailing 3-2 after extra time to claim the inaugural edition of the trophy.

It was a match in which the U.S. navigated myriad twists and turns, rallying twice, converting a pressure-packed penalty through Christian Pulisic in extra time, and then surviving a penalty against them with substitute keeper Ethan Horvath saving brilliantly from Andres Guardado.

There was also the usual venom that accompanies this rivalry. Pulisic and his teammates were showered with debris (and Giovanni Reyna being hit in the hit with an object) after his penalty conversion. There were heavy challenges, more than a few scuffles -- including a hand around the neck of midfielder Weston McKennie -- and even a fan entering the field.

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And in the end, the U.S. prevailed over El Tri in a competitive fixture for the first time in eight years. And while the game carried extra importance with a trophy on the line, the actual prize seemed almost secondary to the events that transpired throughout the evening.

"For this group, it's really important," said U.S. manager Gregg Berhalter about the victory. "We're a young side and we need to learn how to win. These games are very difficult, and for us it was about having a game plan executing the game plan but then it's also about the fight in the spirit."

The future will determine just how much this victory will galvanize the U.S. team. World Cup qualifying starts in a mere three months, and qualification remains by far the most important prize for this side. To a degree, the U.S. men's program is still smarting from its failure to qualify for the 2018 World Cup. But this win means plenty for the players in that it provides a massive boost of confidence that its potential is being translated into results in big moments. It also gives Berhalter the kind of signature win that increases belief in his methods.

At minimum, this is a game that these U.S. players will remember for the rest of their lives, especially given the wild swings in momentum. And none more so than Horvath, who struggled for playing time with Club Brugge this season, and was penciled in as the backup to Steffen. Yet when Steffen was forced off with a knee injury in the 69th minute, Horvath stepped in and made a series of game-changing plays to the delight of the over 20 friends and family who were in attendance.

"Just thinking about how difficult it is for goalkeepers to come into the game, in that stage of the game, and then to make the impact that he made was remarkable," said Berhalter. He added, "It's been a tough season for him and to come and have a performance like that in his hometown was, you know it's stuff that storybooks write about."

The talking point in the run-up to kick-off was Berhalter's decision to go with a three-man backline, presumably in a bid to free up Sergino Dest from his defensive responsibilities and get more into the attack.

But before the U.S. could even settle into any kind of rhythm disaster struck as a too-casual pass from defender Mark McKenzie was picked off by Jesus Corona, allowing him to advance towards goal and rifle his shot past Steffen. The game was a mere 63 seconds old.

The U.S. struggled to settle in during the ensuing minutes, unable to connect passes and looking suspect in defense, especially with Tim Ream often left isolated to defend Uriel Antuna one-on-one.

But a critical sequence around the 27th minute highlighted that as much as the U.S. labored at times both individually and as a team, it showed near-endless reservoirs of resolve, and revealed an ability to learn on the fly. One moment, Hector Moreno nodded home Hector Herrera's cross, only for VAR to come to the U.S. team's rescue and disallow the tally. Then, in a flash, they were level, as Reyna cleaned up a rebound after McKennie's header hit the post. In between, Reyna was everywhere, getting into the attack but also contributing on the defensive end. McKennie began to impose himself all over the field, and John Brooks put in an immense performance to help stabilize the U.S. defense.

There were still warning signs however. Pulisic was ineffective for most of the night. The back line was wobbly. Dest, thought to be a key component in the U.S. breaking down Mexico's defense, looked completely out of sorts, and unsure of what he was supposed to do and where he needed to be.

The second half saw the U.S. play with more composure and on more level terms, even if it wasn't completely in full flow. McKennie forced a trio of saves from Mexico keeper Guillermo Ochoa, as he consistently shook free on set pieces.

And yet it was a substitution from Mexico manager Gerardo "Tata" Martino -- the introduction of attacker Diego Lainez -- that nearly turned the tide. The Mexican side had been attacking Ream relentlessly all game, and Lainez's shiftiness and fresh legs gave him a decided advantage. It paid off in the 79th minute as Lainez cut inside and unleashed a shot that beat Horvath.

At that point, it seemed as though all Mexico had to do was see the game out, yet McKennie wouldn't be denied, finally getting the better of Ochoa with his header from Reyna's corner just creeping into the goal.

The regional heavyweights continued to land haymakers, and Horvath needed to be at his sharpest to deny Lozano in the 90th minute. And if the first 90 minutes delivered drama, extra time took matters beyond the red line. Pulisic won a penalty in the 109th minute after being felled by Mexico defender Carlos Salcedo, one that required a five-minute VAR review, and also saw Martino red carded for placing his hands on the referee. Brooks couldn't stand to watch, facing towards his own goal. He missed seeing Pulisic convert a cold-blooded penalty, and he celebrated by taking off his shirt and shushing the crowd, at which point the U.S. players were pelted with debris. Reyna appeared to take a projectile to the head, though Berhalter said he thinks the attacker "is going to be okay."

Of course, there was one more dose of drama. McKenzie was adjudged to have handled Luis Romo's shot in the box, requiring another lengthy VAR review. Guardado stepped up to take the spot kick, and while his shot lacked placement, it had plenty of power, forcing a spectacular save from Horvath, who admitted he and fellow keepers Steffen and David Ochoa spent 30-40 minutes with goalkeeper coach David Hyde studying the tendencies of the opposition.

"It's down to us doing our homework," said Horvath.

The U.S. then smartly ran out the clock, even as more projectiles rained down on them. At the final whistle, players collapsed to the ground, and were soon celebrating with the U.S. fans behind Horvath's goal.

For the U.S., the tournament has been a rousing success. Yes, the team showed its inexperience in managing big occasions. But it also revealed an adaptability and a mental toughness, even in the face of incidents like one in the second half when Hector Herrera grabbed McKennie.

"I don't know what it is, but they seem to like to grab my neck," McKennie said. "It's a rivalry that's been there for generations and it's rivalry that will still carry on. We just got the upper hand this time, and hopefully it stays that way."

The younger generation is growing up.