Sunderland has confirmed that Jan Kirchhoff will be out for a minimum of six weeks due to a hamstring injury.
The midfielder was forced off early in the second half of Saturday's 1-1 Premier League draw with West Brom at the Stadium of Light.
Manager David Moyes admitted afterwards that he was concerned the problem could be long-lasting, and the club has now announced that it does not expect the former Bayern Munich man to return until late November.
"Jan Kirchhoff has been ruled out for a minimum of six weeks after suffering a hamstring injury during Sunderland's draw against West Bromwich Albion," a statement posted via the club's official website read.
"The former Bayern Munich player was stretchered off in Saturday's game at the Stadium of Light, and in order to assess the extent of the injury the 26-year-old underwent a scan which revealed he will be out for six to eight weeks."
The news comes as a huge blow to Moyes, who has already lost Lee Cattermole (back), Steven Pienaar (hamstring), Adnan Januzaj (ankle) and Seb Larsson (knee) to injuries.
"Not to have him, Steven Pienaar and Adnan Januzaj is massive, because they help us play better and we are short in that area," Moyes said on Saturday. "They are big, big misses to this club.
"If we lose Kirch and we lose Catts, we lose a little bit of the steel and a little bit of the boys who have been here before while we're looking to build a new team."
Sunderland is bottom of the Premier League table, with two draws and five defeats from its opening seven matches.