Cristiano Ronaldo photo: AFP
The five-time Ballon d'Or winner was injured during Saturday's 3-1 win over Al-Fayha.
Al Nassr did not say how long the 41-year-old Portugal star would be out.
“He started a rehabilitation program and will be under evaluation day by day,” the Saudi Pro League team said in a statement.
The extent of Ronaldo's injury was not publicly known. Al Nassr did not specify if it was a strain or tear, and coach Jorge Jesus suggested after the Al-Fayha game that it was “muscle fatigue.”
In photos published Tuesday on Al Nassr's social media channels, Ronaldo was seen training with weights in the team gym.
The five-time Champions League winner is preparing to take part in his sixth World Cup when the United States, Mexico and Canada co-host the tournament this summer.
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