I think that Chelsea, Spurs, Arsenal and Liverpool pretty much have equal chances of finishing beind the 2 Manchester clubs.
Chelsea have been poor recently but do have a strong team, and are all experienced. As soon as they drop Luiz and if Torres can find the goal they will be fine. Arsenal have been a revelation in the last month or 2, if RVP can stay fit then anything can happen! Spurs have been great since the first 2 games, strong squad too and Liverpool have bought very well and just need to turn Anfield into the fortress it was. At this stage, hard to seperate them!