Ronaldo suffered a calf injury in Real's 2-1 victory in the first leg in Madrid and club doctors gave him only a 10 per cent chance of being fit for Wednesday's game.
The Brazilian was included in the squad on Monday, however, and he is now much more optimistic about his chances of making the game.
"I'm well," Ronaldo said on his personal website on Tuesday. "I had a test today and the truth is I feel very well.
"With every hour I'm more optimistic and I now believe I'll be able to play. I'm eager to help the team in a game like this."
