Real Madrid will have to make do without the services of Pepe for a number of weeks due to a thigh injury, making him a doubt for impending clashes with title rivals Atletico Madrid and Barcelona.

The centre-back sustained the problem in Madrid's 4-1 win over Alaves on Saturday, being forced to leave the pitch after just 24 minutes.

He underwent a series of tests to determine the extent of the injury and Madrid have now announced the 33-year-old has been diagnosed with a muscular problem.

"After tests carried out Monday on Pepe at the Sanitas La Moraleja University Hospital, he has been diagnosed with a grade two muscle injury in the femoral biceps of his left leg," an official club statement read.

"His recovery will continue to be monitored."

Reports from Spain suggest Pepe could be out of action for between four to six weeks, meaning he will miss El Derbi against Atletico at the Vicente Calderon on November 19.

Furthermore, the Portugal international could also be in danger of having to sit out the Clasico clash with Barcelona at Camp Nou on December 3.

Pepe's injury provides more bad news for coach Zinedine Zidane, who is already without fellow centre-back Sergio Ramos a knee injury.