The two sides will go head to head at Old Trafford on Tuesday for their quarter-final first leg against the champions.
With regards to league form, Bayern head into the encounter Bundesliga title winners, while United remain seventh in the Premier League table, 10 points adrift of fourth.
"It's a very important tournament for us," the Daily Star quotes Rafael as saying. "Everyone knows it's hard, that's why I am saying we have to play with real quality. We have to show everyone what we are capable of and get a good result."
United will face Bayern following Saturday's 4-1 victory over Aston Villa at Old Trafford.