Ronaldo who was pictured wearing a knee brace this week is set to miss Real Madrid's first three matches against Sevilla on August 9 in addition to two La Liga fixtures against Real Sociedad and Celta Vigo.
His earliest appearance could come on September 11th when Madrid welcome Osasuna to the Santiago Bernabeu.
The 31-year-old is also set to miss out on the opening game of Portugal's 2018 World Cup qualifying campaign against Switzerland.