Bayern took a 2-1 lead back to Munich from the first leg, but after seeing Barcelona crash out after giving up a three goal lead, they were not resting on their laurels.
"Of course that was a warning. It shows that everything can happen in football," Robben said referring to the Barca result.
"If you play at this level, you need a top performance. That will be the case in the semi-final.
"We are now in the semi-finals in the Champions League and in the DFB-Pokal. We have to go a bit further.
"In the semi-finals there are no favourites. We have to see who we get tied up with and then prepare well. There are only good teams left."