Real Madrid are expected to be without key defender Marcelo for up to a month due to a hamstring tear.

The left-back suffered the injury during Madrid's shock 1-0 loss at home to Real Betis in LaLiga on Wednesday.

Madrid released a statement confirming the extent of the injury following scans, with reports in the Spanish media suggesting the Brazil international will not return to action until late October. 

"Following tests carried out on Marcelo at the Sanitas La Moraleja University Hospital, he has been diagnosed with a grade two tear in his left bicep femoris muscle," the statement said.

"His recovery will be monitored."

Marcelo will not feature against Deportivo Alaves on Saturday, and is likely to also miss matches against Espanyol and Getafe in LaLiga, as well as the Champions League meetings with Borussia Dortmund and Tottenham.