German international, Thomas Muler, played a key part in the first Bayern Munich goal by exchanging a clever one-two with Toni Kroos, who then went on to place the ball past Schalke goalkeeper Lars Unnerstall.
Mueller then scored himself by shaking off two defenders and hitting a neat shot into the far corner.
"I feel good physically," Mueller said.
"Anyone who has seen the game also knows that I do not always score. But I have a clear head at the moment and can quickly (get) rid of any negativity.
"For example, I started the second half with plenty of the ball, and I thank my team-mates for threading through the right passes."
Bayern's next match is against Wolfsburg at the Allianz Arena on Tuesday.