Reports before the game had suggested Lopetegui would be sacked regardless of the result, yet Butragueno claims the club are planning to continue as normal ahead of the trip to Camp Nou.
"Lopetegui will sit on the bench at Camp Nou as normal," he told Movistar. "In these kind of situations, it is important to remain calm and trust the players. Sunday's game is a great motivation for us."
Pushed on the rumours Lopetegui would be sacked before El Clasico, Butragueno added: "It is normal. This is football. We have heard the rumours, but we have confidence and hopefully we will play well at Camp Nou."
Goal understands that El Clasico will be a pivotal game for Lopetegui, who could be sacked if his side don't perform against their great rivals.
On Tuesday Madrid were jeered at times against Plzen, with fans turning on the home players as they granted the Czech side chance after chance and passed up opportunities of their own.
Butragueno is keen to improve the atmosphere at the Santiago Bernabeu, adding: "Real Madrid fans want to see their team play well, [and score] goals, goals, goals.
"The fans are very loyal but now we have to change this trend [of jeering]. We respect the public and in these moments we need the support of the people to improve this situation."