Arsenal kicked off their Europa League campaign with a 3-1 Group H victory against Cologne.
Kickoff for the match was delayed by one hour due to concerns over crowd safety as a large number of Cologne fans outside the Emirates Stadium prevented home supporters from accessing the turnstiles, according to Arsenal.
And Cologne wasted no time taking the lead once the game did get underway. A poor David Ospina clearance fell to Jhon Cordoba, who settled, turned and fired a laser from 40 yards out over the Arsenal keeper's head to make it 1-0.
Arsenal, who were making their first appearance in the Europa League since 1999-2000 when it was still the UEFA Cup, nearly drew level minutes later. An Alexis Sanchez cross found Hector Bellerin, but his looping header was tipped over the bar by Cologne goalkeeper Timo Horn.
Theo Walcott was next to try his luck, with the England international dribbling a shot wide of the far post after having been played into the area by Alex Iwobi.
Despite dominating possession in the first half, Arsenal went to the dressing room after 45 minutes trailing their Bundesliga opponents 1-0.
Half-time substitute Sead Kolasinac, a summer signing from Schalke, had an instant impact on the game, smashing home a lovely first-time volley after a deflected Theo Walcott cross fell to him to draw the Gunners level early in the second half.
And soon after, Alexis had Arsenal in front with a fine individual effort, the Chile international cutting in from the left side and curling an unstoppable shot past Horn to put the Gunners ahead 2-1.
Bellerin then sealed the points just past the 80-minute mark after a well-worked team move left him alone on the far post to smash home the rebound from a saved Walcott effort.
Arsenal are away to Belarus outfit BATE Borisov in their next match on Sept. 28, while Cologne play the other Group H match that day at home versus Red Star Belgrade