Crystal Palace's Chadi Riad receives treatment during the Carabao Cup second-round match at Selhurst _(Image: PA)_
Crystal Palace defender Chadi Riad aggravated his knee playing for the Under-21s on Tuesday night.
Riad has been sidelined since August after sustaining an MCL injury against Norwich in the EFL Cup.
The Morrocan international returned to Crystal Palace training at the end of November, with his recovery plan granting minutes for the youth team.
The 21-year-old, who signed for Crystal Palace from Barcelona for £14m in the summer, managed 45 minutes for the Eagles against Anderlecht U21s before being pulled off at the break.
Despite his substitution being pre-planned, Glasner revealed that Riad irritated his knee during the International Cup match.
"He’s a little similar to Adam \[Wharton\]. He had a little bit of a reaction after the game. It looks not that serious, but we had to reduce the impact on his knee.
"It’s something you don't want to have, but something we also know that can happen - especially when you are out for three and a half months.
"Now we have to find the right doses to get him back as soon as possible. He will get all our support to be back as soon as possible."