Athletic Bilbao coach Ernesto Valverde has suffered a double injury blow in preseason.
Yeray Alvarez and Dani Garcia have both been forced out of training this week.
Athletic Club announced on Monday: "Yeray Alvarez has an overload in his right adductor, which prevents him from training at the same pace as his teammates.
"On the other hand, Dani Garcia suffers a sprained left ankle. Both players are awaiting further developments."