Aston Villa midfielder Jack Grealish has been ruled out for at least three months after being admitted to hospital for a kidney injury he suffered in a friendly against Watford on Saturday, the Championship side's manager Steve Bruce said. The 21-year-old was forced off after a collision with Watford midfielder Tom Cleverley and Bruce confirmed that Grealish could be in for a long spell on the sidelines. "It will be at least three months and it could be much longer than that," Bruce told the BBC. "He's poorly at the moment, I went to see him in hospital. "We're obviously disappointed with the injury. He's still in hospital and things aren't great. We hope that he has a speedy recovery, of course, as losing him is a blow to us." Grealish has made 79 appearances for Villa's senior side since 2013 and played in 31 league matches last season.