Wolves defender Jonny Castro is set for a lengthy spell on the sidelines after injuring his anterior cruciate ligament.
Castro suffered the injury in Thursday's win over Olympiakos.
Wolves doctor Matt Perry said: "In the first-half of the match with Olympiacos, Jonny suffered an injury to his right knee.
"A scan confirmed the first clinical impression of an injury to the anterior cruciate ligament, which will require surgical repair.
"This has been arranged and the whole team wish Jonny well on his path to recovery."