The Gunners slipped to one of the great top-flight upsets when they were stunned 2-1 by Hull City at the Emirates Stadium on Saturday, a result which Wenger revealed made him feel physically sick.

Attention has now turned to Europe and a competitive group which also includes Fenerbahce and Dynamo Kiev leaves little margin for error.

But centre-back Kolo Toure is grateful for the early chance for his team to redeem themselves by displaying their character.

"We can't just think about Hull. It's true we lost and didn't play well," he said.

"But we didn't play very well against Fulham and then we came back well in the next game when we beat Twente in the Champions League (qualifiers).

"For a team like Arsenal it's always good to have a good reaction. Any team can fall down but it's about how they react to defeat that matters.

"Tomorrow is a really good test and we will see if we can show another face.

"We are lucky we can play a match so soon after that and change everything in the minds of our fans.

"We want to show everyone we are still a good side. The manager, like everyone at the club, was very upset after Hull.

"If you want to be champions you need to win every game, especially when you play at home. We didn't perform well.

"We're professional and we know that when we play for Arsenal we can't afford to lose like that.

"The manager didn't have to say anything to us but he still had a few words. Every player was very sad and disappointed.

"We need to show we have the character to win against a big team."

Wenger's attacking philosophy has made Arsenal possibly the most attractive side to watch in Europe but Toure had demanded his side deliver more than entertainment.

"We really want to win something this season because we haven't won anything in the last three seasons," he said.

"We are playing good football but we need to win to show that it can win us trophies."

Opponents Porto arrive in London on the back of a 2-0 win over Pacos Ferreira, and have enjoyed an extra day's rest having played their league game on Friday.

The 2004 Champions League winners started this season's European campaign brightly with a 3-1 win over Fenerbahce, and Argentinian forward Lisandro Lopez insists his side want to continue that run against Arsenal.

"We're going to go there to control the game and to win," he said.

However, he added: "But if we can't win, then a draw wouldn't be so bad. The last thing we want is to lose."