I was playing a game a few days ago during the course of wich a unit of Necrons was charged by hormogaunts. The Necrons took 1 casualty and lost the combat. They failed their leadership test and fell back 2. The gaunts sweeping advanced and killed them. The opponent refussed to accept this and came out with sweeping advances cant be used unless your in base contact but since your foe has already fallen back out of base contact this makes sweeping advances impossible. I just want to find out how that should have played out and what the correct rules are. Personaly I reckon he was making excuses.