The Portugal captain and Ballon d'Or winner has missed Real's last four matches, including Wednesday's King's Cup final victory over Barcelona, since limping off during the Champions League quarter-final, first leg against Borussia Dortmund on April 2.
Ronaldo is the leading marksman in La Liga and the Champions League this season and Real coach Carlo Ancelotti will be desperate to have him back to face holders Bayern as Real seek the 10th European crown that has eluded them since their last triumph in 2002.
"Better, much better," Ronaldo told Spanish television broadcaster TVE after Wednesday's Cup final.
"I don't feel any more pain," added the 29-year-old.
"Let's see if Wednesday I am fine or for the second leg. Little by little I am getting better and what I want most is to return as soon as possible to help the team."
The return leg is in Munich on April 29 and the winners will play Atletico Madrid or Chelsea in the final in Lisbon on May 24.
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