Ronaldo is impressed by how United have played this season.
"Every Madridista wants that 10th European Cup - we're more than aware of that," Ronaldo said.
"Last season we fell just short, which was very frustrating. Fortunately we've got the opportunity to set the record straight this year, though the fact we face Manchester United next makes it more difficult.
"It's not going to be easy and I reckon the odds are about 50-50, but I'm still very confident."
He added of the match against his former side United: "No team's unbeatable, but when we're at our best we're a really good side.
"Manchester United have started the English championship race very well and are a long way ahead of the rest, but still, if we play the way we're capable of, we can beat them.
"To do that we need to pull together and play as a team, like we've done in so many matches before."