The Red Devils and Blues sit second and third place in the table respectively after 13 games with eight wins each.
City have by far and away the more potent attacking force, scoring 27 goals to United's 19.
But the Reds have only conceded nine so far, one of which came at Vicarage Road in their 2-1 win on Saturday, while City - who shipped four against Liverpool in their 4-1 defeat last time out - have let in 14.
So which players make it into a Manchester XI playing in the 4-2-3-1 formation favoured by both sides now we are over a third of the way through the campaign?
GK: David De Gea
Probably the toughest choice of the lot, with both 'keepers right up there with the world's best. Hart has done very little wrong and has played more games than his adversary this season but De Gea is just so influential in nearly every game he plays for United. The Spaniard so often makes a crucial save which turns a game in van Gaal's side's favour, including against Watford.
RB: Phil Jones
One of the key men behind United's impressive defensive solidity this season. Versatile Jones gets the nod over Bacary Sagna, who was not helped by his horror showing against Liverpool. Jones was injured in the victory over Watford with a twisted ankle but he has nevertheless been crucial for the Reds so far.
CB: Chris Smailing
One of the most improved defenders in world football, captain Smailing has been head and shoulders United's best player this season. Smailing is a rock at the back but also a threat in his opponents' box. He has come a long way under van Gaal and comfortably makes it into this combined XI.
CB: Vincent Kompany
Another easy choice, Kompany is one of the world's best centre halves and his importance and quality is always highlighted by his absence. Against Liverpool, the Blues struggled badly at the back without the Belgian and the leader is a shoo-in for a place alongside Smailing in what looks an extremely strong pairing.
LB: Alexandar Kolarov
The combined XI gets half and half representation then as Kolarov gets the nod over Ashley Young/Daley Blind. Kolarov is enjoying another impressive season and is always a massive attacking threat both from open play and set pieces with his vicious dead ball strikes. Simply offers more to the all round game than his rivals.
CDM: Bastian Schweinsteiger
Gets the nod over teammate Morgan Schneiderlin for one of the two defensive midfield berths based mainly on the calm assuredness he brings to the side. Got that late winner last time out but Schweinsteiger has showed how crucial he is already this season helping protect the Reds defence and offering a superb range of passing in the engine room.
CDM: Yaya Toure
Perhaps hasn't been at his brilliant best so far this season but Toure offers so much at both ends of the pitch and weighs in with his fair share of goals too. Him and Schweinsteiger would make a pretty fearsome central midfield partnership.
AM: David Silva
The enigmatic little Spanish magician needs no explanation. One of the best players in the Premier League he would walk into most sides on the planet let alone the Manchester XI. Another who is sorely missed by City when he doesn't play.
AM: Kevin De Bryne
Didn't have the best of games against Liverpool but De Bryne has slotted straight back into Premier League life with easy since signing for City. His influence on matches was instantaneous and he would be the perfect foil for the small quick dynamos either side of him. Gets the nod over Anders Herrera.
AM: Juan Mata
The little Spaniard has been instrumental Louis van Gaal’s revolution at Old Trafford. It was a straight shootout between Mata and Sterling for this spot, with Sterling's electric pace making it a tough decision. But only one stat is needed to prove why Mata makes it into the combined XI over Raheem Sterling. Since debuting for Manchster United in January 2014, Juan Mata has been involved in more Premier League goals than any other player at the club. He really is the orchestrator.
ST: Sergio Aguero
One of the best strikers in the world Aguero is by far the best of the combined pool of strikers from both clubs. Another who would walk into most teams in world football, Aguero's power, finishing prowess and bullish strength make him the perfect foil for the attacking trio behind him.