Wolves defender Jonny Otto is likely to be sidelined for up to six weeks after suffering a knee ligament injury on international duty with Spain.
The 24-year-old was replaced in the 51st minute of Sunday's 1-0 friendly win over Bosnia and Herzegovina.
A statement from the Spanish team said he had suffered a partial tear of the internal lateral ligament of his knee.
Otto, who is on a season-long loan from Atletico Madrid, could now be out for the remainder of the year.
He has started every Premier League match for Nuno Espirito Santo's side this season.
Wolves, who are currently 11th in the Premier League table after picking up just one point from their last four games, host Huddersfield this weekend.
Their run of December fixtures includes games against Chelsea, Liverpool and Tottenham.