Vlaar Injured, Cause for Concern?

Aston Villa captain "Concrete" Ron Vlaar has been a crucial piece of the improved backline this season. Unfortunately, he had to leave the game after picking up a calf injury against Southampton the other night. The severity of this injury is still relatively unknown, with seemingly the only thing on the internet about it is a tweet from Mat Kendrick:

Ron Vlaar went off with a calf injury. Villa will assess the severity of it tomorrow to see if he has a chance of facing Fulham #avfc

— Mat Kendrick (@MatKendrick) December 4, 2013

However, that was Wednesday. Today is Friday, and no such updates have been provided. If Vlaar were to be ruled out for an extended period of time, that would be bad news. But, on a plus side, it would rule out that dreaded 5-3-2 bus parking shape employed by Lambert that allowed Villa to have 23% possession score 3 goals in a win against a team that is pushing for a top 6 finish in the Premier League.