Just like the title says, Wanderlei Silva has been pulled out of the fight against Chael Sonnen at UFC 175. Apparently Wandy ran away from a random drug test and therefore won't be able to get licensed.
Vitor has stepped in. The fight will be at 205 lbs, but the winner of the Vitor vs Chael fight at UFC 175 will fight the winner of Lyoto Machida vs Chris Weidman for the Middleweight title. That is as long as Vitor can get licensed by the NSAC.