Sergio Aguero is expected to miss Manchester City's crucial Champions League match against Roma after injuring knee ligaments at the weekend.
The Argentine, 26, was injured in the third minute of Saturday's game against Everton after a challenge with Muhamed Besic. He left the pitch in tears.
City must win Wednesday's game in Rome to have any chance of reaching the last 16 and Aguero's absence is a big blow.
"It's a big problem," admitted City manager Manuel Pellegrini.
"It is very difficult when you have trouble with your ligament to recover in three days."
A Manchester City spokesman told the BBC on Sunday that there was no update about the player's injury.
Aguero - the Premier League's top scorer with 14 goals - limped out of Saturday's match, which City won 1-0, and was replaced by teenager Jose Pozo.
Pellegrini, who was already without Yaya Toure for the Roma game due to suspension, revealed Aguero was "more calm" in the dressing room afterwards.
Match of the Day Presenter Gary Lineker said on Twitter: "Worrying-looking knee injury sustained by Sergio Aguero.
"Anything serious would be a massive blow to him, Manchester City, and football lovers everywhere."
Aguero has earned widespread acclaim for his performances this season, with Pellegrini hailing the striker as "one of the best players in the world".