MILLWALL winger Paris Cowan-Hall sustained a hairline fracture to his tibia during Tuesday's 0-0 draw with Reading, the club has announced.
A specialist has also diagnosed that Cowan-Hall damaged ligaments at the back of his knee.
The Lions have not put a timescale on his recovery but it appears the January signing will be sidelined for the foreseeable future.
Physio Bobby Bacic told the club's official site: "Paris has already seen one specialist and he will have a second opinion next week before a decision is made on whether surgery will be required to repair the small stabilising ligament.
"The alternative, pending the outcome of that decision, is to take a conservative approach and allow the ligament to heal naturally.
"Although the news is a huge blow to Paris and to the club, a crumb of comfort can be taken from the fact that these injuries usually happen alongside the more significant crucial ligaments, which in this case, thankfully, are intact.
"We will update everyone after Paris has his appointment."