INGLEWOOD, Calif. — The last kick of Thursday’s 3-2 loss to Turkey is a reminder that the United States men’s national team is entering the phase of the World Cup where one moment, action or mistake can define their legacy.The U.S. did its job in the first portion of this tournament. They won their group and got the country behind them. Even the disappointing loss to Turkey with a heavily rotated squad won’t extinguish all of those positive vibes.But the legacy of this national team will not be defined by what they did in the past three games. It will be written on July 1 and beyond. U.S. coach Mauricio Pochettino understands that better than anyone. It’s why he batted away a question about this being a missed opportunity to make history by winning three group games for the first time.“To make history is to win a World Cup, it’s not to win three games in a World Cup,” Pochettino said in his native Spanish. “It’s a little bit petty, no, or thinking in too small terms. You have the chance to make history. What’s the point of winning three matches only to lose the next one and miss out on (winning) the World Cup?”USMNT fans on the marchTom BogertKaan Ayhan’s last-second winner for Turkey should be a warning shot to this team of the thin margin between a good result and disappointment. The room for error going into the knockouts becomes paper-thin.The U.S. will face a Bosnia and Herzegovina team that will be the lowest-rated the U.S. has ever played in a knockout tie, according to the ELO ratings. But the do-or-die nature of the game doesn’t allow them to underestimate the opponent.They can look all around this World Cup tournament to see supposedly weaker teams extracting wins and points out of favorites.“There’s no different feeling for us (being favored),” U.S. captain Tim Ream said. “We expected to be top of the group, we wanted to be top of the group. We’ve done that. And we know that we have the ability and we have the players and we have the talent, we have the togetherness and everything that we need to move on and win knockout games.”The game against Turkey was a survive-and-advance moment. Rotate players into the team. Try to stay healthy — to be determined on that front after Auston Trusty’s ankle injury. And then move into the knockout mindset.For the most part, the vibes afterwards among U.S. players remained positive — frustrated, yes, but positive. The team completed its objective of finishing at the top of the group. Thursday, with nine changes to the starting lineup, was a chance for players to make a claim on a bigger role or to fulfill their dreams of playing in a World Cup.The gut punch of the goal at the final whistle was difficult, but players said they had to turn the page quickly. The round of 32 awaits in six days.When the final whistle sounded, it signaled a transition. Pochettino was miffed he didn’t get congratulated for winning the group; I’d argue he’d just gotten a full week of it from just about every angle in this country. Attention and eyes had to turn to what comes next. Now he must bottle up as many positives from those group wins and move forward into a knockout round that brings a different type of challenge.Mauricio Pochettino was unhappy with the reporters’ line of questioning after the Turkey defeat. (Jamie Squire / Getty Images)This U.S. team learned four years ago that games can turn quickly in the knockouts, especially when the quality of the opponent starts to increase. Bosnia is not the Netherlands, but in the round of 16 in Qatar, the U.S. saw how ruthless the real contenders can be on these big stages. The U.S. needs to operate on a similar level.“When we look back at ’22, we made a couple of mistakes against the Netherlands and that cost us being in the tournament longer,” said Tim Weah, who then said he felt to blame for Turkey’s second goal. “Those little mistakes are something you have to fix. But I believe in this team. We’ve done such a great job to get to this point.”Winger Alejandro Zendejas regularly plays in knockout competitions in Mexico. He emphasized the importance of getting every small moment right against Bosnia.“It’s about the details and concentration and the little stuff, that’s what’s going to matter in these types of games,” Zendejas said. “We’re prepared, we’re ready. We’ve demonstrated in these past three games that we’re a tough team to play against.”The U.S. has to become even more potent. It has to play its cleanest games. And it has to embrace the pressure of the moment.A loss to Bosnia would change how people remember this tournament, flipping it from the fun, celebratory vibes of those first two games to asking where it stands among the biggest World Cup flops. That’s the nature of these types of competitions. Getting through the group stage ticked off one box. Just one U.S. team, in 2002, has ever won a World Cup knockout game. This is a chance to change another narrative around the program.But to do that, you have to win.As Zlatan Ibrahimovic said on Thursday night on Fox: “Now starts the real deal.”