Robin Le Normand took a step closer to recovery from the injury in Atletico Madrid training this week.
The Spanish international has not appeared since a clash of heads with Real Madrid star Aurelien Tchouameni in the final seconds of Los Rojiblancos' 1-1 derby last month.
After the game, Le Normand was sent for urgent tests, which confirmed a brain injury and a subdural hematoma.
The club is understood to have opted for extreme caution over the situation, due to the severity of the injury, and has not been called up for Spain duty in October.
Despite confidence in him being able to return to match action in early November, Diego Simeone He confirmed that he is not clear on the return date, with tentative steps taken.
According to the latest update from The world of sportsLe Normand has now taken a limited part in training, but the real test will come when he moves into contact sessions in the coming weeks.
No risk will be taken for his return with the potential of an absence extending until 2025.
