Athletic Bilbao are set to be without Inaki Williams for Thursday's Europa League quarter-final second leg against Sevilla due to a hamstring injury.
Williams scored the only goal in Athletic's Liga victory over Rayo Vallecano on Sunday but was substituted shortly after his 61st-minute strike and the club confirmed a problem with the 21-year-old's left thigh in a statement on Monday.
It read: "Inaki Williams has an overload on the back of his left thigh.
"His availability will depend on its evolution over the coming days."
Williams has enjoyed a breakthrough campaign with Athletic this season, scoring 13 times in 32 matches across all competitions and winning Spain Under-21 honours.