The 28-year-old star was crocked during the Capital One Cup at Norwich.
Bent limped out of the quarter-final tie at Carrow Road after only half an hour - his first start for six weeks.
The England international underwent a scan on Wednesday and Villa manager Paul Lambert is resigned to being without the club's record signing "for a few weeks".
Lambert said: "He went for a scan on Wednesday and he has got a problem with his hamstring which will keep him out for a few weeks.
Asked if he was out of the Christmas matches, the Scot added: "Yes, probably, the way it is looking, yes.
"I think a few weeks. Maybe four weeks, I'd say, before we see him back."