Panama hit back to earn a 1-1 draw against United States, denying the Gold Cup hosts a victory to open the tournament.
USA looked like they were heading for victory in Nashville when Dom Dwyer continued a dream start to his international career, scoring for the second straight game early in the second half.
But Panama forged a strong response and Miguel Camargo, who plays his club football for New York City, ensured the first match in Group B ended level.
The two teams have recent Gold Cup history, USA having beaten Panama in the 2013 final, before losing to the same opposition in the 2015 third-place play-off.
Martinique and Nicaragua are the other two teams in the group.
The hosts threatened first when Kelyn Rowe cut inside from the left and unleashed a dipping shot that was unconvincingly parried by goalkeeper Jose Calderon.
A short USA corner then led to a left-footed drive from Kellyn Acosta being pushed away by Calderon.
Bruce Arena's men squandered the best chance of the half as Acosta set up Rowe from 15 yards, but he could only send his drive straight at Calderon, who was growing in confidence.
After a slow start, Panama responded impressively, with Camargo's curling effort from the corner of the box tipped wide by Brad Guzan at full stretch.
Ismael Diaz then cut inside and dragged a shot inches wide at the end of a first half that ended level.
USA struck first five minutes into the second half. Super work from Rowe down the left saw him work space for himself before delivering a cross for Dwyer to finish first time, left-footed from eight yards
Panama responded well to falling behind and should have been level when Diaz somehow blazed over from a yard out after Gabriel Torres' header had been saved by Guzan.
Camargo and Edgar Barcenas had also fired inches off-target before the equaliser arrived on the hour mark.
Barcenas worked the opportunity with impressive play down the right, which set up Torres, whose initial strike was saved before Camargo showed desire to force his way onto the rebound and beat Guzan with low effort.The contest slowed after the equaliser, with no major late incidents other than USA captain Alejandro Bedoya having a penalty claim denied after tangling with defender Luis Ovalle, the five-time winners left to reflect on a match that showed the road to Gold Cup glory will not be easy.