As the Costa thing is 100% the refs call at this stage (i.e. different to leage games, no panel to make judgement) then I can't see this going any further. Oliver will bottle it, like he does all major decisions. There's no way he saw the stamp at the time, he gave the freekick for the foul before it, and his view was blocked by Henderson, yet I wouldn't be surprised if he claimed he did see it. Alternatively he could bottle it ans claim he felt it was accidental, or only worthy of a yellow card (this is most likely for me), but either way there's not a great deal of chance that Costa gets the 3 game ban his action actually warrants.