Mikel Arteta has said that Arsenal are missing "that little thing" which could transform them into a side capable of challenging for major honours.

The Gunners travel to the Allianz Arena for the second leg of their Champions League last-16 tie with Bayern Munich tomorrow, but find themselves 3-1 down after the first leg three weeks ago.

The Spaniard has admitted that he and his teammates have an uphill task awaiting them in Germany but said that last year's performance against AC Milan has given them a ray of hope.

"It will be very tough, they were very good in the first leg and it will be even harder away from home," Arteta told The Mirror. "The psychological thing is very important. We had a great example of how that can happen last year against Milan.

"After a very disappointing result in the first leg, we scored a goal, score another one and it's a completely different game. We have to get ourselves in that position again.

"We have that spirit. We've had disappointments in the past few years. We have a very good team but we are missing that little thing which makes a difference and that's where we need to find the key."

Arteta joined Arsenal from Everton last season.