The Bayern Munich striker has scored four goals in his first three matches at the tournament, and his teammate feels that Joachim Low's side's past failures in major competitions have been down to the 24-year-old's absence.
Neuer told reporters: "[Muller] is at the top level. He comes alive in a World Cup. But in the last two major tournaments he did not start the semi-finals and on both occasions we lost the game.
"So we hope he will be okay and ready for the next games."
Germany take on Algeria in their second-round clash on Monday.