Vlaar missed last weekend's defeat against Arsenal, which sent Villa back into the bottom three of the table, with a calf injury.
"Ron is doing okay at the minute and I need to monitor him and how he is going to be," Villa manager Paul Lambert said on the club's website (www.avfc.co.uk) on Friday.
"We've still got a few days to see how he progresses. We will have to wait and see.
"He would be a big miss because I think he has been playing really well of late."
Striker Darren Bent is still struggling with a foot injury and will miss the match but goalkeeper Shay Given has recovered from a groin strain and should be in the squad to face his former team.