The tie remains finely balanced, with Bayern carrying a 2-1 advantage from the first leg in Madrid. Neuer had been the difference in that match, producing nine saves to earn man-of-the-match honours while keeping Kylian Mbappe and Vinicius Junior largely quiet.
Now 40, Neuer is approaching the end of his contract and has yet to decide on his future. Injuries have limited him to fewer appearances this season, but his importance to the team remains clear.
Club CEO Jan-Christian Dreesen said: "We had something Real didn't - our world-class goalkeeper, our x-factor."
Defender Jonathan Tah added: "He simply exudes something special. You shouldn't take it for granted, but for him it's normal."
Head coach Vincent Kompany also underlined Neuer's influence off the pitch. "Manu only has to say one sentence and he brings order to the team," he said. "His leadership is just as important as what he does on the pitch."
Despite their first-leg lead, Bayern remain wary of Madrid's pedigree in Europe. Joshua Kimmich warned: "When it's the Champions League, they perform."
Leon Goretzka added: "It's a brutally difficult task. We know how quickly they can create chances."
Neuer also has unfinished business. He made a costly error in Bayern's semi-final exit to Madrid two years ago, a moment that still lingers.
With the decisive second leg still to come on Wednesday, Bayern once again look to their captain to deliver - both with his saves and his leadership - as they aim to finish the job and reach the semi-finals.
