LONDON, ENGLAND - FEBRUARY 16: Dejected Arsenal players Mikel Arteta (L) and Jack Wilshere (R) look on as Blackburn players celebrate their team's 1-0 victory during the FA Cup with Budweiser fifth round match between Arsenal and Blackburn Rovers at Emirates Stadium on February 16, 2013 in London, England. (Photo by Shaun Botterill/Getty Images)

Dublin – There may be worse ways to prepare for a match against one of the best teams in Europe than by losing at home to a team from a lower division. But Arsène Wenger would probably be as hard-pressed to think of one as he was to explain how Blackburn Rovers had become the first team from outside the Premier League to end his interest in the FA Cup.

Definitely not to blame, he said, was his decision to rest key players ahead of tomorrow evening's Champions League tie against Bayern Munich at the Emirates Stadium. A lack of mental maturity in the team was the more likely culprit – and he has called for a response against the leaders of the Bundesliga, although he admits that confidence will have to be repaired if Arsenal are to have a chance.

“We are still to show maturity on the mental front, to understand what it means to win big games,” he said. “It was a certainly big game for me and it is important that we come back and respond well. Honestly, you look at our team and we had basically the regular defence. You had (Mikel) Arteta, (Abou) Diaby, (Tomas) Rosicky, Gervinho, (Alex) Oxlade-Chamberlain, (Olivier) Giroud – they are regular players, for me. So (to blame team selection) would be a wrong way of thinking. I am the first to be responsible for the team selection but that would be an easy excuse. If we can't beat Blackburn like that I don't think the explanation is purely down to the selection of the team.

“We were on quite a high because we played well at Sunderland last week and the team looked very happy, full of belief, but couldn't maintain their focus. And what is top level is consistency in every single game and that's what we could not show. We came out with a flat performance and that shows that mentally we are not capable of preparing exactly the same for every single game.”

Wenger acknowledged that one possible symptom of that mental fragility was subconsciously expecting an easy game against a team they had beaten 7-1 last season, even though Wenger had emphasised to his squad the importance of the match and the FA Cup – realistically the club's best chance for a first trophy since 2005.

“Yes, but maybe they still thought: 'We're playing at home, we're playing against Blackburn, it will work – OK, it may be difficult but anyway we will win the game.' But it doesn't work like that.”

Of course, it could be said that Wenger had sent out that very signal by resting Jack Wilshere, Santi Cazorla, Lukas Podolski and Theo Walcott. But at least, by that logic, the players will raise their game against the superior challenge posed by Bayern, when nobody will be under any illusions about the size of the task. Certainly not Wilshere, whose introduction after 70 minutes of Saturday's game injected urgency into a side that was running out of steam after a bright start had not brought a breakthrough. The England midfield player knows Arsenal cannot afford another loss of concentration, however brief, such as the one that gave Blackburn their winning goal with their only on-target shot.

“We've got to regroup now,” he said. “We know what Bayern are capable of and they've got a great team. It's not ideal to go into a game like that after the loss today but we have to show our character now.

“We've beaten big European teams here before so we need to do that again. We need a good defensive display and then we need to counter them well. They've got a good defensive unit as well so it's going to be an interesting game and we look forward to it now.”

Bayern appear to have improved since they reached last season's Champions League final, losing to Chelsea on penalties, but Wilshere believes that their London rivals showed how a team can overcome indifferent domestic form in Europe.

“I think that was an inspiration for everyone,” he said. “Chelsea weren't having a good season and they got a bit lucky in some games but showed great character. We need to do that. We need to come together as a team.

“(On Saturday) the fans were naturally disappointed and we accept that, but tomorrow we need to have everyone behind us.”

In Saturday's post-match gloom, talk of emulating Chelsea's surprise Champions League victory sounded fanciful, as Wenger admitted, but the Frenchman was not certainly prepared to concede defeat.

“Just now it would be a bit pretentious to say that but you never know,” he said. “We have to come out with a strong response, we have to give it a good shot tomorrow night and see where we stand after the game.”

Misfiring Gunners AFC slump in stats:

Saturday's loss was their first FA Cup exit to a lower-division team since Wenger arrived 17 years ago

28 – Years since Arsenal went out of both cups to a lower-division side

31 – Trophies Arsenal have missed out on since their last success – the 2005 FA Cup. – The Independent