Franck Ribery and Bastian Schweinsteiger were the latest two players to be ruled out of the last eight clash due to an ankle injury and illness respectively.
They joined Arjen Robben (stomach), Medhi Benatia (hamstring), David Alaba and Javi Martinez (both knee) on the sidelines, leaving Bayern short of numbers.
Pep Guardiola was only able to name four substitutes for the Bundesliga win over Eintracht Frankfurt at the weekend, but Muller believes the Bavarian giants can still triumph in the face of adversity.
"The squad has the experience to play without some of our important players and because of this we move together," he said. "We know that we have not so many opportunities to change at the moment.
"Because of this we moved together. This can be very important and helpful. The competition between the players in our team isn't as fierce as in other times. We have to build a unity on the pitch.
"The last matches against Leverkusen, Dortmund and Frankfurt were good experiences for us. We are very self-confident and trust each other."
