However it has been confirmed that striker Darren Bent will be sidelined for 10 days with the knee injury he suffered during the Capital One Cup semi-final first-leg defeat at Bradford.
Villa manager Paul Lambert said: "Darren's injury is not so bad but we are looking at maybe 10 days or so out."
Dutch defender Vlaar has been out of action with a calf injury since sustaining the setback during the goalless draw with Arsenal on November 24, but the summer signing from Feyenoord returned to training on Thursday.
Lambert indicated Vlaar will be part of the squad against Southampton if he comes through Friday's session at Bodymoor Heath unscathed.
Lambert said: "Ron is a very experienced player. He has been out for the best part of two months and we have certainly missed him.
"He trained yesterday and hopefully he will train today. We will see how he is but if he comes through okay, he will be part of the squad for tomorrow."
Bent has had an injury-hit season and suffered his latest setback after being introduced as a substitute at Valley Parade.
Goalkeeper Shay Given also sustained a hamstring injury against the Bantams but first choice Brad Guzan was expected to return against Southampton.