The forward suffered the injury on World Cup duty with Brazil.
Real Madrid forward Vinicius Junior is facing a spell on the sidelines after being injured during Brazil’s World Cup qualifying defeat against Colombia.
The Spanish club said he had been diagnosed with “a tear in his left femoral bicep”.
“Following tests carried out today on our player Vinicius Jr by the Real Madrid medical services, he has been diagnosed with a tear in his left femoral bicep which is affecting the tendon in his hamstring,” Real Madrid said.
“His recovery will be monitored.”
Vinicius, who will miss next week’s appointment with Argentina, went off midway through the first half and becomes the latest Real Madrid player to suffer an injury setback.
Midfielder Eduardo Camavinga (knee) and goalkeeper Kepa Arrizabalaga (thigh) are among those currently sidelined, while England international Jude Bellingham is nursing a shoulder problem.