The sides were drawn together on Monday and will do battle over two legs for a place in the quarter-finals.
While Real finished Group B unbeaten, Ancelotti does not want his side to take their Bundesliga opponents, who came second in Group E behind Chelsea, lightly.
"It is a very important competition and we have to be ready and do the maximum," the Italian told Real's official website.
"These are knockout-round encounters, and it is always ...
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