Thomas Muller said he felt his side had played "10 against 14" in their Champions League defeat at Real Madrid on Tuesday.
Bayern were angered by several key decisions by referee Viktor Kassai, feeling that the sending off of Arturo Vidal was unjust and that two of Cristiano Ronaldo's three goals were offside.
Muller told reporters: "If you look at the way things went, it is extremely difficult when you are playing with 10 against 14.
"The [goal that made it] 2-2 was the worst situation -- the assistant referee had a great view. That killed us."