Wolves will be without Jonny Castro Otto for the next six weeks.
The wing back suffered a knee injury in Spain's 1-0 win over Bosnia.
And after tests, it appears he has a partial ligament tear.
A statement from the Spanish FA confirmed the news: "(Otto) suffered a partial tear of the internal lateral ligament of his knee, that has been detected in the tests carried out on the morning of this Monday.
"It is estimated an absence of five or six weeks."
He is set to miss eight Premier League games if he is out for the full six weeks.