Schalke's USA international midfielder Weston McKennie is expected to be out of action for some time after dislocating his shoulder in the Royal Blues' 1-0 victory at home to Eintracht Frankfurt on Sunday.
The 21-year-old started on the left of a three-man backline for David Wagner's side owing to an ongoing defensive injury crisis that already has Salif Sane (knee), Matija Nastasic (knee) and Benjamin Stambouli (metatarsal) in the treatment room.
However, McKennie lasted just 13 minutes before being stretchered off and replaced by Juan Miranda following an aerial duel with Frankfurt striker Bas Dost.
Wagner confirmed on Sunday that McKennie was in hospital with a dislocated shoulder, but was unable to say whether or not he would need surgery, other than stating that "he will definitely be out for a while".
McKennie has made 13 Bundesliga appearances for the Royal Blues this term, starting 10, and has been a key figure in the club's rise to fourth in the standings.
Schalke are next in action away to Wolfsburg on Wednesday before playing their final fixture of the year at home to Freiburg on Saturday.