The forward picked up the knock during the defeat to Manchester City on Wednesday.
Speaking ahead of Villa’s game against Leicester tomorrow, boss Steven Gerrard said: “Unfortunately he’s had a scan and that has confirmed there is a muscle injury.
“It’s going to be quite a long one so he’ll be missing for a number of weeks, you won’t see him before Christmas.”
Gerrard was waiting until today before naming his squad for the Foxes clash – with the boss wanting to give fellow injured duo Matt Targett (head) and Danny Ings (hamstring) every chance to be available.
“Matty Targett will probably struggle for this game, but we’ll make a late decision on him and Danny Ings,” the boss said.