Villa suffered a 3-0 defeat against Manchester City, with all the goals coming in the second half for the home side.
The 24-year-old played till 86th minute before being replaced by Anwar El Ghazi. He picked up a calf injury during the game.
Dean Smith said after the game that the club skipper will be assessed in the coming days.
According to the Birmingham Mail, Grealish is now a major doubt ahead of Wednesday’s crunch Carabao Cup clash with Wolves.
Grealish has said on Twitter that he hopes that the injury isn’t too serious.