After Leicester grabbed a stupidly late winner yesterday (YOU HAD ONE JOB, NORWICH), the gap between Arsenal and first place is five points. Not insurmountable, sure, but Arsenal have to keep pace; a win today is vital if Arsenal want to stay in the conversation about the championship.
Fortunately, Arsenal head up to Old Trafford in reasonable shape, minus of course the newly absent Alex Oxlade-Chamberlain. For once, a match that has the words "injury crisis" attached to it does not refer to Arsenal; Manchester United are missing the likes of Wayne Rooney, Marouane Fellaini, Bastian Schweinsteiger, and Luke Young definitely out and several other players facing late fitness tests.
In other words, United are there for the taking; Arsenal are in a good run of league form right now, and a third consecutive win in the league would be the perfect way to start a Sunday.