Atalanta, Georgia: Panama pulled off a shock 2-1 victory over the United States in a heated Group C encounter at the Copa America on Thursday after the hosts were reduced to 10 men following Tim Weah's red card in the 18th minute.
Jose Fajardo netted the winner in the 83rd minute for Panama, who had Adalberto Carrasquilla dismissed five minutes later for a crunching challenge on Christian Pulisic.
The US are second in the group, level with Panama on three points but with a better goal difference. The hosts must at least match Panama's result in the final group game to advance to the knockout rounds.
The US play Uruguay while Panama face Bolivia on Monday.
"Emotional rollercoaster, but that's soccer at the end of the day," US midfielder Tyler Adams said.
"We know what we signed up for and playing in Copa America we knew it was going to be a fight. Credit to Panama. They did their job. They got the result."
Panama coach Thomas Christiansen said his team had executed the game plan perfectly.
"I'm very happy, in particular for the team, tactically and psychologically," he added.
"I try to make the best decisions by being calm, level-minded. And of course, everyone that went in contributed what we expected from them, and now we have a victory such as this one."
It was a costly night all round for the hosts, with goalkeeper Matt Turner being substituted at halftime with a leg injury after a collision with Panama defender Cesar Blackman in the 12th minute.
Weah was sent off after a video review showed he had shoved Roderick Miller in the back of the head off the ball amid a tense and fiery start to the match.
After Weah's dismissal, Folarin Balogun delighted the crowd with a splendid strike from 17 yards to give the hosts the lead in the 22nd minute. However, the joy was shortlived as Blackman equalised from the edge of the box four minutes later.
"There were things before the red card that went against us," Balogun said. "Of course, we probably could have had a few decisions, but that's the nature of the game."
Ethan Horvath replaced the injured Turner in the US goal at the break and nearly faced a penalty in the 64th minute but the decision against US defender Cameron Carter-Vickers was overturned by video review.
The best opportunity for the US in the second half came in the 81st minute when a header by Ricardo Pepi was saved by Panama goalkeeper Orlando Mosquera.
Panama then seized the initiative, scoring the winning goal when substitute Fajardo smashed home Abdiel Ayarza's cross.
"Moving forward, we need to control our emotions in certain situations," Adams said. "I think the team fought for everything after we got the red card. You definitely can't fault the effort.
"By winning the first game, we put still ourselves in a position that we can have everything to play for in the last game."
Weah had apologised to the team after the match, he added.
"Just respect to the rest of the team because they fought for every single ball, every single duel, every single minute, and we still created chances after going down 10 men, so it shows our quality."