The 30-year-old French left-back lasted only ten minutes of Sunday's 2-0 win at Espanyol before going off, his body language on the way down leaving little doubt about the severity of what had occurred.
Real Madrid's official medical statement was brief.
"Following tests carried out today on our player Ferland Mendy by the Real Madrid Medical Services, he has been diagnosed with a tendon injury in the rectus femoris of his right leg. Awaiting progress."
The club confirmed that specialists and the player will assess the surgical option in the coming days, describing an operation as the most likely course of action. A recovery timeline of approximately five months is anticipated, depending on the outcome of that decision.
It is Mendy's fifth injury of this campaign alone, and the latest chapter in an injury record at Real Madrid that has become genuinely alarming in its scale. Since joining from Lyon in 2019, the defender has sustained around 20 injuries, the vast majority muscular rather than the result of contact or trauma. He has now missed approximately 129 matches across his time at the club, accumulating more than 700 days of absence in total — close to two full calendar years.
This season amounted to 448 minutes on the pitch across nine appearances. When fit, he showed his quality, particularly against Bayern Munich in the Champions League, where he dealt effectively with the threat of Michael Olise.
With the World Cup in the summer, Mendy's international career also hangs in the balance. He has not represented France since June 2024 and was considered unlikely to feature in Didier Deschamps's squad even before this latest setback.