Schalke 04 manager David Wagner disclosed that Amine Harit is a doubt for their league match against Borussia Monchengladbach.
Harit is struggling with a thigh problem and could miss their first game of the year after the winter break.
The 22-year-old has played in every of the Royal Blues' Bundesliga matches and has contributed six goals with four assists this season.
Ahead of Friday's clash against second-placed Borussia Monchengladbach, Wagner is uncertain if the Moroccan midfielder will feature in the encounter.
"Apart from our long-term injuries, almost everyone is fit.