Barcelona goalkeeper Marc-Andre ter Stegen could miss the rest of the season injured after the Catalan club said Monday he had completed knee surgery following a tendon rupture.
The 32-year-old German international was taken off on a stretcher after falling awkwardly during his team's 5-1 La Liga victory over Villarreal on Sunday.
"(Ter Stegen) has a complete rupture in the patella tendon in his right knee," said Barcelona in a statement, with the club later confirming the goalkeeper had been successfully operated on.
Spanish reports suggest he will miss around eight months, which means he is unlikely to appear for the club again in the current campaign.
Ter Stegen, who was criticised after making a mistake in Barcelona's 2-1 Champions League defeat at Monaco on Thursday, suffered the injury before half-time at Villarreal's Estadio de la Ceramica.
"I think it will be a huge injury, when he lay down on the field... you can see it directly," Barcelona coach Hansi Flick said after the game.
Inaki Pena replaced Ter Stegen and is set to fill in for the German, although Barcelona may look to sign a replacement.
Flick said it was too soon to comment on the issue.
"I don't know if I like this question directly after the match... I just want to see how Marc is, he's our captain and is a very important player for us," said Flick.
"Please understand that I don't want to talk about that."
Pena, 25, made 12 La Liga appearances for Barcelona last season while Ter Stegen was sidelined with a back problem.
Ter Stegen started two Nations League matches for Germany in September after Bayern Munich veteran Manuel Neuer's retirement from international duty in August.
Germany could turn to Stuttgart's Alexander Nuebel, on loan from Bayern Munich, or Hoffenheim veteran Oliver Baumann as their number one.
"The news of Marc's injury came as a great shock to us. He will be sorely missed in the national team, both on and off the pitch," said Germany coach Julian Nagelsmann.
"We will always be there for him on his road back."
Ter Stegen was also offered support by Real Madrid coach Carlo Ancelotti.
"I want to say that I'm really sorry for Ter Stegen... I hope he can recover soon," Ancelotti told reporters.
"He's one of the best goalkeepers in the world. I hope his recovery is as quick as possible."