Ronaldo put United in the driving seat for tonight's Champions League quarter-final return at Old Trafford.
But Vucinic said: "We have to be angry after what happened last week.
"If we didn't come here feeling angry it would be a waste of time.
"We only have 90 minutes to put it right but we believe we have half a chance."
United boss Alex Ferguson insisted: "Ronaldo deals with these things in the proper way. He gets up and asks for the ball again."