Athletic Bilbao winger Iker Muniain will miss the Basques' Copa del Rey final against Barcelona after suffering a cruciate ligament injury, the club confirmed on Tuesday.
Muniain had to be stretchered off in tears during Athletic's 2-0 defeat to Sevilla on Saturday and is set to be out for at least six months.
"A torn cruciate ligament has been detected in his left knee," said a statement on the club's website after the player underwent a scan.
"The estimated time out oscillates between six and seven months."
Muniain has only one senior Spanish cap to his name, but was part of the under-21 sides that won the European Championships in 2011 and 2013.
Athletic face Barca in the Cup final for the third time in seven years on May 30.