Chelsea striker Armando Broja suffered a serious right knee injury during a 1-0 friendly loss to Aston Villa in Abu Dhabi on Sunday with manager Graham Potter admitting "it doesn't look positive".
The 21-year-old Albanian international was hurt when he collided with Villa's Ezri Konsa in the first half.
Broja was left screaming in pain before being taken off on a stretcher.
"It was an unfortunate action, I think he got caught up with their player and the ground," Potter told Chelsea's official website.
"It doesn't look positive at the moment, but it is too early to say. Fingers crossed, but it is an awkward one."
Broja has made 12 appearances in the Premier League this season, 10 of them off the bench and scored one goal.
Chelsea will resume their Premier League season following the World Cup break on December 27 when they welcome Bournemouth to Stamford Bridge.
They are eighth in the table, 16 points behind leaders Arsenal after a three-game losing run.
A productive week away. ??#AbuDhabiBlues pic.twitter.com/t1HxFu1dV1
— Chelsea FC (@ChelseaFC) December 11, 2022