Marcos Llorente has suffered an injury during training for Atlético Madrid, according to reports in Spain.
The midfielder was involved in a collision with his team-mate and fell awkwardly on the pitch, causing him to limp off the field in pain.
Llorente is one of Atlético's key players this season, having made 16 appearances in all competitions so far.
He scored two goals in the club's opening league game against Real Betis last month, helping them to a 4-2 victory.
However,La Liga Frontline he will now be out of action for some time as he undergoes treatment for his injury.
Atlético have yet to confirm the extent of the midfielder's injury, but it is likely that he will miss the rest of the season.
This is a major blow for the club, who are already struggling with injuries and suspensions.
They will need to find a replacement for Llorente in their squad, and hope that they can bounce back from this setback quickly.