A frantic opening paved the way for an exhilarating, blood and thunder match in which both teams had a player sent off.

The first 26 minutes in Atlanta saw USA have a goal disallowed, Timothy Weah sent off and Folarin Balogun score a stunner before Cesar Blackman equalised.

With the match seemingly ebbing towards a draw, Ricardo Pepi's profligacy sparked a frenetic finale, with Jose Fajardo netting in the 83rd minute and Panama holding firm despite Adalberto Carrasquilla's red card.

Victory takes Panama level on three points with the Copa America host, which is in a precarious position ahead of facing Uruguay in its final Group C match.

A rowdy crowd was almost silenced inside the first two minutes when Yoel Barcenas' stunning bicycle kick flashed over the crossbar, but the home fans were soon celebrating when Weston McKennie slammed in, only for the goal to be disallowed after a lengthy VAR review for Tim Ream straying offside. 

There was further VAR frustration to come for USA, as it was reduced to 10 men when Weah saw a yellow card upgraded to a straight red after he lashed out at Amir Murillo.

That frustration turned to elation in the 22nd minute as Balogun brilliantly fired in from the edge of the box, his left-footed strike cannoning in off the inside of the right-hand upright.

It was a lead that lasted only four minutes – Blackman drilling into the bottom-left corner from 20 yards out to restore parity.

VAR came to USA's rescue just after the hour when referee Ivan Barton overturned his decision to award Panama a penalty after Cameron Carter-Vickers lunged in on Fajardo.

Balogun went close to a sensational second soon after, but the best chance of the second half fell to his replacement Pepi, whose close-range header was kept out by Orlando Mosquera.

Pepi was immediately made to pay, with Fajardo making no mistake as he lashed home from close range, and even though Carrasquilla saw red, Panama sealed a memorable victory that throws Group C wide open.

Pepi has had to settle for a substitute role with Balogun the first choice, but that has not stopped him having chances. In fact, he has accumulated more expected goals (2.27) than any other player in the tournament so far.

Yet the youngster, who has played just 43 minutes, has failed to convert any of his seven shots, while the other four players in the top five for xG at this edition of the Copa have all scored at least once.

McKennie did brilliantly to tee Pepi up for USA's big moment in the second half, but PSV striker fluffed his lines.

In contrast, Balogun showed just how good he can be – his goal, his second of the tournament, came from a shot with an xG value of just 0.04. The Stars and Stripes might well need their first-choice forward to deliver that kind of quality again if they are to progress.

Panama came out on top on penalties against USA in the Gold Cup last year, but Thomas Christiansen's team was well worth its victory in regulation time on this occasion.

USA did continue their run of scoring at least one goal when facing Panama – they have now done that in 19 of the last 20 meetings – but despite the hosts having a higher xG (1.11 to 0.76), Panama had the cutting edge when it mattered.

It had to play dirty at times, committing 19 fouls to USA's four, and Gregg Berhalter may well point to that, but mastering the dark arts has given Panama, which faces Bolivia next, a great chance of getting out of the group.