Yannick Carrasco is a doubt for Atletico Madrid's Champions League last-16 first leg against Chelsea next week after suffering a leg injury.
Atleti on Friday revealed Belgium international Carrasco has sustained an injury setback but did not specify how long he will be out of action.
A club statement said: "Yannick Carrasco has suffered a post-traumatic injury of the left leg musculature, an MRI scan and a medical ultrasound performed at the Clinica Universidad de Navarra confirmed the injury. The Belgian is pending response to treatment."
LaLiga leaders Atleti face Levante at the Wanda Metropolitano on Saturday, before taking on Chelsea at the neutral venue of the Arena Nationala in Bucharest three days later.
Carrasco only recently returned after missing three matches following his positive coronavirus test.
There was better news on midfielder Thomas Lemar, who is back in contention after recovering from COVID-19, while Moussa Dembele is nearing a return.
Diego Simeone told a news conference: "Yannick has a knock from the game against Granada. It's still affecting him. We'll see how it evolves.
"The good news is Lemar is with us and we look forward to Dembele possibly being able to return tomorrow and to continue adding people as quickly as possible."
Simeone's side are six points clear of second-placed Real Madrid with a game in hand after they were held to a 1-1 draw with Levante on Wednesday.