MADRID (AFP) - Real Madrid's Portuguese star Cristiano Ronaldo will miss Saturday's derby against Atletico Madrid, the club's assistant coach Aitor Karanka confirmed on Friday.

Ronaldo, 28, picked up a thigh strain in Wednesday's crushing 4-1 Champions League semi-final, first leg defeat at Borussia Dortmund and did barely five minutes of jogging on Friday before returning to the indoor gym at Real's training complex, Spanish media reported.

"He has a muscle problem and he wasn't able to train today and he isn't in the squad for tomorrow," Karanka said.

"We hope to have him back for the return match against Dortmund," he added.

Resting Ronaldo gives him an extra three days to recover in time for the second leg against Dortmund on Tuesday.

Real need to get a result in the derby to maintain their hold on second place in La Liga with their city rivals just three points behind in third.

Ronaldo, the top scorer in the Champions League this season with 12 goals, had been thought to be certain to start against Dortmund in the Bernabeu but Friday's news has caused some to question that theory.

"At Real they said the Portuguese was sure to play in the semi-final second leg but Friday's training session has instilled some doubt," sports paper Marca said on their internet site.