The Seleccao face an uphill task to progress to the quarter-finals, having been drawn with three former European champions in Germany, Netherlands and Denmark.
But Ronaldo thinks that Portugal may be the surprise package of the group and insists that the favourites tag is an extra source of pressure.
"We know we are in the most difficult group of the Euros, but it is not anything to regret, because you cannot change it, and we have known it for months," he told Uefa.com.
"So we have to be prepared, we have no other option. These will be extremely difficult matches, but I think Portugal will do a good job and we will progress to the next phase.
|Portugal are 18/1 with Paddy Power to go all they way and win Euro 2012.
I have faith, because the favourites do not always win, and we are not on the list of favourites, which takes a bit of pressure off our players."
The 27-year-old then highlighted the importance of the team getting off to good start with a victory against Germany on Saturday.
"We obviously want to win, because we want to start the Euros well," Ronaldo explained. "Germany are a great team, they have had great results in recent competitions, so we respect them a lot.
"But we also have our strengths and we will do everything to start the Euros on the right foot.
"We have everything we need and we just have to be calm because things will go well.
"I hope the future will be good for us and that we will win something important, because we have a great team and a great coach, so we have to aim to win something important."