But the Portugal international hoped it would be a 'magical night' for his team, who are aiming for their 10th European Cup.
In what will be Real's first Champions League final since 2002, Ronaldo said the May 24 decider was too close to call.
"It’s a moment which the club has been waiting for for a long time. It’s going to be a great final, an exciting match between two great teams," Ronaldo said.
"Finals are always 50-50.
"We just hope that it’s a fantastic night and we win. We hope that May 24 will be a magical night for Real Madrid."
Ronaldo was full of praise for Diego Simeone's Atletico, who are top of La Liga by three points and well-placed to win the title.
"They're a fantastic side and it's not by chance that they're top of the table. That says a lot about them," he said.
"It’s nice that we have an all-Spanish final – it shows how strong the national league is.
"And let's not forget that Sevilla are in the Europa League final too."
Real already have the Copa del Rey trophy locked away this season, and they could add the Champions League and La Liga.
While winning the league is unlikely – Real are four points behind Atletico with two games remaining – Ronaldo said it had been a good season.
"f we had known at the start of the season that we would be in this position, we would have been very satisfied," he said.
"We've won the Copa del Rey. The league is looking difficult but not impossible and we're in the Champions League final."
