Hoffenheim currently sit 16th in the league and would drop to an automatic relegation place if they lose to 17th-placed Augsburg.
"Now, nerves of steel are required," Bundesliga.de quotes Muller as saying. "Each player has to be motivated to show that he is better than his opposite number.
"Fear has no place in football nothing. Each player just has to take responsibility and look to improve as a team."
Hoffenheim have picked up four points in the five games for which Muller has been in charge.