Luton lose - We lose - Portsmouth win one and draw one - Sunderland win both matches. All 4 would finish up with 91 points. Luton and us go up on goal difference.
Well statistically speaking it's not zero though it would be low. Putting those set of results into sky bet (with Pompey drawing tomorrow as seems more likely of the two) gives you 969/1. If that did happen Sunderland could pass us on GD with a couple of decent wins. Still Sunderland will surely throw a 1-1 into the last two games.