The Portuguese Football Federation (FPF) confirmed on Wednesday that the Real Madrid star is suffering from tendinosis in his left knee in addition to a thigh problem that kept him out of last weekend's 0-0 draw with Greece.
It remains to be seen whether Ronaldo will be fit in time for the World Cup, which starts a week on Thursday, and his potential absence would be a boost to the hopes of Portugal's Group G rivals Ghana.
Ghana face Portugal in their final group game on June 26 and Nana Kwaku Bonsam, the country's most influential witch doctor, believes he has delivered on a promise he made in February to keep Ronaldo out of action.
"I know what Cristiano Ronaldo’s injury is about, I'm working on him," Bonsam is reported as saying on Ghanaian radio station Angel FM.
"I am very serious about it. Last week, I went around looking for four dogs and I got them to be used in manufacturing a special spirit called Kahwiri Kapam.
"I said it four months ago that I will work on Cristiano Ronaldo seriously and rule him out of the World Cup or at least prevent him from playing against Ghana and the best thing I can do is to keep him out through injury.
"This injury can never be cured by any medic, they can never see what is causing the injury because it is spiritual. Today, it is his knee, tomorrow it is his thigh, next day it is something else."
Portugal start their World Cup campaign against Germany in Salvador on June 16.
