Riyadh | Cristiano Ronaldo has sustained a hamstring injury, his club Al Nassr said Tuesday without giving a timeline for the Portugal star's return.

The five-time Ballon d'Or winner was injured during Saturday's 3-1 win over Al-Fayha.

"He started a rehabilitation program and will be under evaluation day by day," the Saudi Pro League team said in a statement.

Al Nassr did not specify if it was a strain or tear, and coach Jorge Jesus had suggested after the game it was "muscle fatigue." In photos published Tuesday on Al Nassr's social media channels, the 41-year-old 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. The United States, Mexico and Canada will co-host the tournament this summer.