ATLANTA — Tim Weah is usually as cool and graceful on the soccer field as off it, but in a moment of madness Thursday, the 24-year-old winger put the U.S. national team in a terrible spot. And because of it, a berth in the Copa América quarterfinals now hangs in the balance.

Weah received a red card in the 18th minute for punching an opponent on the back of the head, leaving his team shorthanded for most a 2-1 defeat to Panama.

Despite the situation, the Americans actually took the lead after Weah’s dismissal on Folarin Balogun’s sensational goal in the 22nd minute. But Panama used its man advantage to answer quickly and place the United States under persistent duress before going ahead on José Fajardo’s 83rd-minute goal.

Even a draw would have created high drama entering the Group C finale Monday against Uruguay in Kansas City, Mo. But because it lost, the United States (1-1-0) is almost certainly going to need to beat the group favorites. Uruguay (1-0-0), 15-time champions of this event, played Bolivia (0-1-0) late Thursday.

Panama (1-1-0) also finished with 10 men after Adalberto Carrasquilla was red-carded for a brutal foul on Christian Pulisic in the 88th minute. By then, however, Fajardo, a former D.C. United striker, had scored on an eight-yard one-timer off back-up goalkeeper Ethan Horvath’s hands before 59,145 at Mercedes-Benz Stadium.

The U.S. team’s visit was a longtime coming for Atlanta, which, since the arrival of an MLS team in 2017, has become a hotbed for the sport. Atlanta United has been a box-office hit, its attendance averaging more than 47,000 the previous two seasons, but because the stadium is equipped with artificial turf, the U.S. Soccer Federation has been reluctant to schedule matches there.

It did, though, put down grass in April for the SheBelieves Cup women’s tournament, which drew 50,644.

Grass was also installed for Copa América by South American tournament organizers — though an imperfect one, according to Argentina, which complained about it after its opener last week.

The U.S. men’s team had not played in Atlanta since a semifinal loss to Jamaica in the 2015 Concacaf Gold Cup at Georgia Dome.

Although the U.S. team had lost just two of the previous 26 meetings, Panama has become a thorny opponent. The teams split their 2022 World Cup qualifiers, each winning at home, and Panama prevailed in a shootout in the 2023 Concacaf Gold Cup semifinals.

Panama lost its Copa América opener to Uruguay, 3-1, on Sunday, but a late goal provided a silver lining and a dose of belief heading into the U.S. match.

U.S. Coach Gregg Berhalter did not make any lineup changes from the 2-0 victory over Bolivia on Sunday. Including two tournament tuneups this month, nine players have started four consecutive matches.

The only alternating has come at defensive midfield (Johnny Cardoso, Yunus Musah and Tyler Adams) and striker (Balogun and Ricardo Pepi).

Berhalter typically does some tinkering between matches, but for the first time since the 2021 Gold Cup quarterfinal and semifinal, he stuck with the same group. And for the first time since 2011, the United States fielded the same four-man back line in four consecutive games.

As they did against Bolivia, the Americans executed a set piece to score — except this one did not count.

In the fifth minute, goalkeeper Orlando Mosquera pushed Chris Richards’s header off the crossbar, then the post. Tim Ream touched the rebound back to Weston McKennie for a 12-yard one-timer, but long after the celebration died down, referee Iván Barton used video replay to determine Ream had been offside on Pulisic’s free kick.

Eleven minutes later, Weah was expelled for punching Roderick Miller during an off-the-ball exchange. Initially a yellow card, Barton turned to video replay again before upgrading it to red.

Nonetheless, the United States went ahead in the 22nd minute on Balogun’s breathtaking smash. Antonee Robinson intercepted a pass deep in Panama’s end and exchanged passes with Balogun. The striker’s rasping one-timer from the top of the penalty area kissed high off the far post and into the net for his second goal of the tournament and fifth of his U.S. career.

Panama answered four minutes later. Robinson disrupted Cesar Blackman’s initial bid from the top of the box, but Blackman stayed with it and drove a slithering shot beyond Matt Turner’s reach and into the left corner.

As the contentiousness continued, Panama posed multiple threats. The undermanned Americans were bending. The halftime whistle brought relief.

Berhalter turned to his bench for injury and tactical reasons. Turner, who had been treated for a right shoulder ailment following a first-half collision, was unable to continue and yielded to Horvath. Cardoso replaced Adams and, with the U.S. team needing defensive reinforcement, attacker Gio Reyna was sacrificed to accommodate center back Cameron Carter-Vickers.

Panama made multiple changes early in the half, hungry to win the match but also reassured that a draw would leave it in decent position entering its group finale against Bolivia.

Barton and video replay were in the center of attention again in the 63rd minute, when he awarded a penalty kick to Panama. But after review, Barton determined Carter-Vickers had not fouled Fajardo.

The Americans had a chance to go ahead in the 81st minute on Pepi’s header off McKennie’s cross. But Panama made the most of its late chance, throwing the group into disarray with one set of matches left.