Real Madrid defender Eder Militao is set to miss the majority of the season after suffering a cruciate ligament injury, days after goalkeeper Thibaut Courtois suffered the same problem.

The Brazil defender went down hurt in Los Blancos' 2-0 win at Athletic Bilbao on Saturday at San Mames, their first match of the season in La Liga and left the pitch in tears.

"(Militao) has been diagnosed with a rupture of the anterior cruciate ligament in his left knee," Madrid said Sunday in a statement.

The club confirmed the 25-year-old will take surgery on the injury in the coming days.

Madrid are poised to sign Kepa Arrizabalaga from Chelsea on loan to replace Courtois.

They have cover for Militao in the squad, including Germany international Antonio Rudiger and versatile defender Nacho, who can play alongside David Alaba.

Courtois suffered his knee injury in training on Thursday ahead of the start of the season and will also undertake surgery.