Manager Arsene Wenger hopes Arsenal will produce a positive response in the Champions League this week after being handed a "shock to the system" by their 1-0 away defeat at Norwich.
The Gunners never really got going against a side which had leaked goals in recent weeks but stepped up their performance to stun the Gunners.
Arsenal enjoyed plenty of possession as Norwich defended deep, but could not carve out any meaningful openings.
Wenger knows Arsenal need to produce a much-improved display when they take on Schalke aiming to secure a place in the last 16 of the Champions League.
"I hope it will have a positive impact," Wenger said. "It was a shock to the system, but you have to give credit to Norwich because they played well, were completely committed and they deserved the win.
"Maybe we underrated the difficulty we would face, but the Premier League is the Premier League - if you are not ready for the fight then you will always have bad surprises.
"It was a shock to the system, but you have to give credit to Norwich because they played well" - Arsene Wenger
"There is a big difference between the amount of possession we had and the amount of chances we created, that is down to the fact that Norwich defended well and we did not create a lot."
As with every international break, nearly all of Wenger's first-team squad were away, while Norwich still had the majority of the group to work with.
Wenger, though, was not about to hold it up as an excuse.
"We have to deal with that," he said. "You could say we have better players but there is only one way to show that, on the football pitch."
Arsenal had included England midfielder Jack Wilshere in the squad for the first time in 14 months as he steps up his recovery from ankle and knee problems.
However, the 20-year-old is not expected to be in contention for the midweek European tie as he will feature for the under-21s at Everton tomorrow.
Definitely out is England winger Alex Oxlade-Chamberlain, who had to go off with a hip injury against Norwich just 10 minutes after coming on in the second half.
"I don't see anyone new being (back) for Wednesday night," Wenger added. "The closest will be (Kieran) Gibbs, but he will not be ready. (Theo) Walcott will not be ready."