the michael redd curse
it just a sprain though
dude needs to work on his mechanics though, both times he injured the knee it was on that awkward long plant he does which basically puts all his body weight on the knee for a split second which cause the his knee to buckle.
I suspect the only reason why it didn't tear this time, is because your acl is actually stronger after acl surgery done correctly because they use a piece of the platella tendon which is stronger than a normal acl