Selly did the maths in the Pigs thread in the other football section. Praise Selly not me I'm merely copying and pasting;
They will have 13 games remaining after the Derby. That's a maximum of 39 points.
If they finish the game 40 points or more behind 4th from bottom then they will be down. In order for us to relegate them they would need to be fewer than 43 behind 4th from bottom (because if they are 43 behind 4th from bottom they are already down)
So:
if they enter the game with us 39 or fewer points behind - we cannot relegate them*
if they enter the game with us 40 points behind and we win, they go down**
if they enter the game with us 41 points behind and we win OR draw, they go down**
if they enter the game with us 42 points behind and we win OR draw, they go down**
if they enter the game with us 43+points behind they are already down**
* If we happen to be 4th from bottom then there are some scenarios where we can relegate them depending on how far they are behind 5th from bottom, but frankly the permutations are too complex for me to bother doing the maths
** Subject to any pending points deduction applied to teams like, for example, Leicester City. It's possible they could be mathematically relegated - then not relegated - then mathematically relegated again...
NOTE: They are already 37 points behind 4th from bottom...