Brazilian forward, Vinicius Jr tore a ligament in his right leg during Real Madrid’s 4-1 defeat by Ajax in the Champions League last-16 second leg.
The 18-year-old Brazilian winger was forced off in tears after 35 minutes at the Bernabeu on Tuesday night and was replaced by Marco Asensio.
Real said in a statement on Wednesday morning that scans revealed he had suffered “a torn ligament of the tibiofibular joint of the right leg”.
But they were unable to give a return date for Vinicius.
The statement said: “Following the tests carried out today on our player, Vinicius Jr, by the Real Madrid medical department, he has been diagnosed with a ligament tear of the tibiofibular joint of the right leg.
“His recovery will continue to be assessed.”
Lucas Vazquez, another Real winger, was also prematurely removed due to injury. He was replaced by Gareth Bale after 29 minutes.
Real were already 2-0 down when the pair were taken off, but things got worse as they conceded two more and – although Asensio pulled one back – they were eliminated from the Champions League for the first time since May 2015, crashing out 5-3 on aggregate.