Fellow Serie A sides Atalanta and Lazio also won, while Portugal's Vitoria Guimaraes began their match against Salzburg with not a single European player on the team.
Arsenal's Europa League match at home to FC Cologne was delayed by an hour. "A year ago it didn't work out against Liverpool and Arsenal, but this season we have already won at Tottenham", Courtois said.
Wenger, however, believes domestic success is key to Arsenal's ambitions after dropping out of the top four for the first time in 20 years.
Cologne coach Peter Stoger refused to be questioned on the actions of the club's supporters: "I have no comment about the fans", he said.
Before Arsenal turn their attention to champions Chelsea, they face a tricky test at home against Germany's Cologne in the Europa League on Thursday.More news: Coordinated IS attack in Iraq kills 50
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The Chilean's wonderstrike, sandwiched between second-half goals from teammates Sead Kolasinac and Hector Bellerin, was the stand-out moment in a match that kicked off an hour late. I don't know, was it mental? "He's a fantastic football player but physically, he is just coming back".
They went into the break with boos ringing around the stadium and trailing 1-0 following a wonder goal from Jhon Cordoba. It is early days, Gooners, but do you think that instead of a pain in the backside we do not want or need, could the Europa League actually be a nice ray of sunshine for Arsenal? They now rank dead last through three games, with just one goal scored and a huge seven surrendered.
"You can lose games, but you simply cannot concede ten goals - even against Bayern in the Champions League".
"It is a good opportunity to show we can cope", Wenger said.
"It's a new competition for us and we had to set the tone, " he said.
"Wednesday night or Thursday night is no different for us, apart from the fact that it's a different competition, but when you play Wednesday-Saturday it's similar to Thursday-Sunday", the Frenchman said this week.