The left-back launched an inexplicable assault on compatriot Ben Moukandjo towards the end of their loss to Croatia, but escaped a sending off as none of the officials saw it
The African nation were being outplayed in a must-win match against the Balkan side and were four goals and a man down with a minute left on the clock when the QPR left-back, on loan from Tottenham, snapped.
He whipped in an inch-perfect cross for substitute striker Pierre Webo to crash against the crossbar via the ground and his overhead kick follow-up could not be directed past his Croatian marker.
After the attack has dissipated, Assou-Ekotto went over to Ben Moukandjo - who had been lingering on the edge of the box when the defender had crossed for Webo - and started shouting at him.
Moukandjo attempted to walk past, looking downtrodden, but Assou-Ekotto suddenly lent in to attack the 25-year-old, who looked shocked at his team-mate.
The referee and his fellow officials missed the incident, so Assou-Ekotto has so far escaped being reprimanded, while injured Cameroon skipper Samuel Eto'o could be seen comforting a distressed Moukandjo after the final whistle.
Earlier in the first half, Alex Song elbowed Croatia striker Mario Mandzukic in the back, resulting in the Barcelona midfielder being given a straight red card.
The defeat in Manaus saw Cameroon become the third team to be eliminated from the World Cup, despite them still having a game against Brazil to play on Monday.
Their tournament has been plagued by an internal dispute over potential win bonuses, which ultimately proved pointless as the Indomitable Lions look set to exit the competition without a victory.