Arsenal will conduct a full review to determine how vast numbers of Cologne supporters gained access to the home sections of the Emirates Stadium.
Arsene Wenger thought Arsenal's Europa League game against Cologne would be called off because of the fan trouble outside the Emirates Stadium.
Everton boss Ronald Koeman apologised to the club's fans after the dismal 3-0 Europa League defeat to Atalanta and stressed he was responsible.
A porous defence, a lack of energy, and no attack contributed to yet another loss for Everton.
Steve Nicol and Shaka Hislop question how much Arsenal's win over Cologne will help them heading into their clash against Chelsea.
Arsene Wenger praised Arsenal's second-half performance and spoke about the delay caused by travelling Cologne fans.