Muller played 12 years for the Royal Blues before working a further nine as the club's director of sport and general manager before being relieved of his duties in March 2009.
"All of that counts for nothing," he said. "We want the points. We must not show the face we showed in Mainz again, that really annoyed me what happened there.
"We want to see passion and engagement, from every single player and from the first to the last minute, then we can beat a good side like Schalke."
Those were precisely the characteristics which Muller showed in 266 appearances for the Royal Blues, making him the kind of player Hoffenheim coach Markus Babbel needs in his side right now after picking up just two points in the last four games.
Schalke, meanwhile, have amassed 10 points in the same number of games to edge even closer to the summit.
A win tomorrow [Saturday] would take them to within a point of league leaders Bayern Munich before their trip to Hamburg in the evening.
Including games in the DFB-Pokal and the Champions League, Schalke have gone eight games unbeaten, but despite such a busy schedule, their coach Huub Stevens feels his side are not suffering.
"We have a fit squad," he said. "We just have to show our quality in the game."
Lars Unnerstall is set to keep his place in goal, despite Timo Hildebrand this week complaining about his lack of chances.
"That is not an issue," said Stevens. "Every player should be disappointed if they are not playing and they have to prove themselves in training. Ralf Fahrmann also wants to play."