The talismanic Portuguese forward last played on May 24 in Real Madrid's victory in the Champions League final but has been hit by minor injuries throughout the season.
Portugal's opening World Cup fixture is against Germany in Salvador on June 16.
Here's why CR7 won't arrive fully fit for the World Cup:
1. Ronaldo hasn't been 100 percent fit since May 7 when he left a La Liga game against Valladolid with pain in his left leg.
2. Ronaldo hasn't had time off since July of last year, leading many to think he is suffering from fatigue.
3. Ronaldo's playing in the Champions League Final didn't do his recovery any good.
4. Even though he was advised to take rest, he went to the Ballon d'Or ceremony, played against Atletico and went to the celebrations.
5. Demands on the body have left him with two injuries, according to the medical staff of the Portuguese Football Federation.
6. Injury to the back of his left thigh may take up to three months to heal.
7. Left patellar tendinitis is the injury recently detected, which can require weeks or months of recovery.
8. If Ronaldo doesn’t take care of himself, his patellar tendon could tear, which would require surgery.
9. Paulo Bento, coach of the Portuguese national team, said to media he would not risk the health of any player.
10. Real Madrid would not want Cristiano Ronaldo to be overexposed in Brazil because if something worse happens, he might miss out on the beginning of the new Spanish season.