Mourinho, who on Saturday night surrendered his nine-year, 150-game unbeaten record in league home matches when Real Madrid lost to Sporting Gijon, had previously ruled Ronaldo out of the game with a hamstring problem.
However, Mourinho will meet with his top scorer, as well as the injured Karim Benzema and Marcelo, to establish whether the three players are willing to take a gamble on their fitness of the game at the Bernabeu.
"If he [Ronaldo] has a chance it's because he and his coach are taking a risk, because the information from the medical department is that he can't play, that he can only play in the game in Bilbao [next weekend]," Mourinho said.
"But if the two of us and only the two of us decide that he's going to play then the risk is mine and his. Tomorrow I will talk with the injured players and decide if we will risk them."
Even if Ronaldo is unable to declare his availability then at least Real saw the unexpected return of Gonzalo Higuain to first-team action on Saturday night. The striker had not played since November after undergoing surgery on a herniated disc but returned ahead of schedule to play against Sporting.
Higuain said: "On an individual level I'm very happy. People believed I would miss the entire season, but I managed to show that statistics aren't everything in life. It was not a challenge or a competition with anybody, it was a matter of pride for myself to show that I could be back ahead of schedule.
"I was able to achieve that and I feel very comfortable. The key to the recovery was fighting hard, not letting myself get down and battling for what I love most, which is to play football.
"I'm grateful to all the coaching staff, the doctors, fans, my team-mates, my family and to myself. I'm very happy to be able to feel like a player again, although this wasn't quite the dream comeback I was hoping for."