[link to www.dailymail.co.uk]

Chaos erupted 36 minutes into Ajax's clash with AZ Alkmaar at the Amsterdam Arena stadium last night after the drunk 19-year-old ran onto the pitch.

AZ Alkmaar's Costa Rican keeper Esteban Alvarado spotted him launching his flying-kick and skillfuly tripped him - before launching into his own attack with a series of his own kicks.

Security guards dragged the supporter away, before referee Bas Nijhuis red carded the keeper for violence. Alkmaar coach Gertjan Verbeek then ordered his side to walk out in protest.

Nijhuis said: 'I understand that Esteban was defending himself, but he walked to him (the supporter) and kicked him multiple times. He could also have walked away.'

Ajax coach Frank de Boer, a renowned former defender for Netherlands' national team, said of Alvarado's reaction: 'Maybe I would have done the same thing, maybe not. But emotionally I do understand it.'