Panama held Mexico to a 1-1 draw in a bad-tempered Gold Cup clash in Houston that ended in chaos after three players and Mexico boss Javier Aguirre were sent off.
There were ugly scenes at the final whistle as angry fans tossed litter onto the pitch and fights broke out in the stands, where the 47,000 crowd was dominated by Mexico fans.
Problems began after Ricardo Phillips ran the ball into touch in front of the Mexico bench 10 minutes before time and got into a shoving match with Aguirre, prompting several players to wade in.
Phillips was shown red and Aguirre ordered from the bench, but things did not settle down as the trouble transferred into the crowd and the game was held up for several minutes.
Further trouble came when Blas Perez, scorer of the Panama goal, was struck by a missile from the crowd in the final minute. After receiving treatment, he was hit again as he was being stretchered off.
Both teams were already down to 10 men at that point as Mexico's Luis Noriega and Panama's Armando Gun were sent off on the stroke of half-time when a scuffle broke out following a foul by Gun on Giovani Dos Santos.
It was Dos Santos who teed up Miguel Sabah to put Mexico ahead after just nine minutes, but Perez levelled shortly before the half-hour mark.
The draw leaves Mexico needing a point from their final group game against Guadeloupe to ensure qualification for the quarter-finals. Should they lose and Panama beat Nicaragua, Mexico could be on their way home.
Guadeloupe are through to the quarterfinals after two goals in two minutes from Stephane Auvray and Ludovic Gotin gave them a 2-0 win over Nicaragua, keeping them top in Group C.
Aurelien Capoue set up both strikes, which came in the 58th and 59th minutes.
Guadeloupe have the maximum six points from their two games after beating Panama 2-1 in the opener, taking the pressure off as they prepare to face Mexico in the final group game.