According to Villa's twitter feed, captain Ron Vlaar will be out for a period of four to six weeks with a knee injury.
Ron has been plagued with knee injuries since 2008 and has had a number of knee problems this year, especially off of the back of a great 2014 World Cup campaign for the Dutchman.
The good news? Villa won't be able to sell Ron in January (he will fail a medical) and Okore/Clark will get more games together to solidify the partnership they started to build in late-2014. The bad news? I think this is gutting for Ron, he is obviously a talented footballer and this injury is starting to become a real problem for him and could scupper his future. I would only want Ron to be in a Villa shirt, but it would be such a shame for him to have to end his career earlier than expected, especially if he is destined to play at a much higher level.
Get well soon Ron!