The Egyptian club Al Ahli have confirmed that defender Alex Telles has sustained a knee ligament tear in his right knee during training.
Telles, who joined the club from Manchester United last summer, was involved in training on Monday and was immediately taken to hospital for treatment.
The Brazilian international is expected to miss up to six months due to the injury, which occurred during a tackle with teammate Ahmed Musa.
Al Ahli's medical team has already been informed of the situation and will now work closely with Telles' family to ensure they receive the best possible care.
In a statement released by the club, manager Hassan Shehata said: "We are deeply saddened to learn about the injury suffered by Alex Telles during training this morning.
"His health and well-being are our top priority at Al Ahli and we will do everything in our power to support him and his family through this difficult time."
The news comes as a blow to Al Ahli,Chinese Super League Matches who were looking to strengthen their defence ahead of the upcoming season.
Telles' departure could leave the club short of experienced defenders in the heart of their backline, but the club will hope to find suitable replacements quickly.
In the meantime, the club will be without one of their key players for the foreseeable future, but they will still look to compete in the league and in all competitions.
It remains to be seen how long Telles will be out injured, but it is clear that the club will need to make changes to their squad if he is to recover fully.