World Cup 2014: Assou-Ekotto headbutt 'unimaginable'
Cameroon coach Volker Finke said he will find out why Benoit Assou-Ekotto headbutted team-mate Benjamin Moukandjo during the 4-0 defeat by Croatia.
The pair were arguing in injury time before the Tottenham defender thrust his head at the forward.
"It's unimaginable. I saw this happen and I need to find out exactly what happened, why exactly these two players exploded," said Finke.
"I hate to see that. It's not the image of Cameroon I want to project."
The incident almost continued in the tunnel, but injured striker Samuel Eto'o, who watched the match from the sidelines, stepped in the way of Assou-Ekotto, who spent last season on loan at QPR, helping them win promotion to the Premier League.
Cameroon's second defeat in Brazil eliminates them from the tournament and means the African side have now failed to reach the second round of the World Cup in their last five attempts.
They fell behind to an Ivica Olic goal in the 11th minute, before they were reduced to 10 men when midfielder Alex Song swung his arm into the back of Mario Mandzukic.
Song later apologised for his part in the off-the-ball scuffle with Mandzukic, with the 26-year-old Barcelona midfielder asking for forgiveness.
"I'm very sad at the moment as I feel I have let my country and myself down," said Song.
"It was a stupid moment and I'm truly sorry. If I could do anything to take it back I would. Please forgive me."
Ivan Perisic added a second soon after the restart, before Mandzukic scored twice to give Croatia their first victory of the tournament.
"I apologise for the result, it really hurts," added Finke.
"We had no control on the game and I didn't like the behaviour of my team. We have to look forward - this team has players for the future."
Croatia's win means victory over Mexico in their final Group A game would guarantee them passage through to the second round for the first time since 1998.
"We have to rest up well - the boys used up a lot of strength today," said coach Niko Kovac.
"Then we'll go into what is effectively a final for us and will do everything we can to progress."
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