Real Madrid’s Brazilian forward Vinicius Jr could be out for two months after tearing ligaments in his right ankle during the defeat by Ajax.
The reigning champions lost 4-1 on Tuesday as they were knocked out of the Champions League in the last 16.
The 18-year-old left the pitch in tears during the first half at the Bernabeu.
A Real Madrid statement said Vinicius, who received his first Brazil call-up last week, has a “torn ligament of the tibiofibular joint in the right leg”.
The striker has made 28 appearances this season for Real after joining from Brazilian side Flamengo in the summer.
Real, who had won three successive Champions League titles before this week’s exit, sit third in La Liga and are 12 points behind leaders Barcelona after their El Clasico defeat on Saturday.
They have now lost four successive games at home for the third time in the club’s history.
The young Brazilian is expected to be dropped from Brazil’s squad that will play friendlies against Panama and the Czech Republic later this month.
Real Madrid said exams on Wednesday showed a ligament tear in his right ankle. The club did not say how much time Vinicius Junior will need to recover, but Spanish media said similar injuries usually keep players sidelined for about eight weeks.
Vinicius Junior was hurt at the end of a long run in which he nearly scored for Madrid on Tuesday in the first half of the game against Ajax at the Santiago Bernabeu Stadium. He tried to continue after being attended by doctors but was soon taken off. The youngster cried as he made his way back to the bench, loudly applauded by fans.
The speedy and skilful forward recently took over Gareth Bale’s spot in Madrid’s starting lineup. He had been playing well but endured some criticism for missing too many clear chances in front of goal.
The loss to Ajax eliminated Madrid from the Champions League, ending its three-year reign as champion. It was the team’s fourth consecutive home loss in all competitions, following two against Barcelona in the Copa del Rey and the Spanish league, results that left Madrid without a realistic chance of winning anything for the rest of the season.
The 18-year-old Vinicius Junior joined Madrid last year after the Spanish team paid 45 million euros ($51 million) to Brazilian club Flamengo.
Madrid’s next match is Sunday against Valladolid in the Spanish league, a competition in which it trails leader Barcelona by 12 points with 12 matches left.