Since the 1-1 draw in the first leg in Madrid last month, the Spanish champions have beaten Barcelona twice in succession.
The Portuguese told reporters: "We have hit our best form. Apart from [Iker] Casillas we have everyone available and the manager (Jose Mourinho) has great solutions on the bench.
"We have achieved two important victories given the form and quality of the opponent we were playing and that gives us great motivation for the Manchester United game.
"We are happy and now we need to rest and think about the game on Tuesday."
The sides meet at Old Trafford on Tuesday evening.