Andy stays at #13 next week
Looking ahead to the following week, if Andy wins Memphis, he picks up 190 points giving him a total of 1840. This means he can potentially pass Berdych (unless Berdych makes the semis). He could also pass Haas who is defending his title at Memphis (unless Haas makes the semis). Nalbandian is still out of reach. Otherwise, the best Andy can do is to maintain at #13.
So, win Memphis: best result #11, worst result #13
otherwise, best result #13.
edit: if Andy wins Memphis, Djokovic can't pass him and niether can Ferrer, although if Ferrer wins Rotterdam he will have 1835 points.