updates on Derrick Johnson's knee injury

He appears to be seriously injured on his knee yesterday. Hopefully, this is minor. But, if it is significant, who will be the beneficiary?

Judging my Romeo Crennel's most recent comments, Johnson just seems to have twisted his ankle. I would assume he should be good to go Week 1. If he were to miss time, Brandon Siler would most likely be inserted as a started, not sure if he would be a three down backer, however.