The hosts will refuse to admit it, but the Gunners miss departed striker Robin van Persie.
Arsenal sold van Persie to Manchester United over the summer in the name of fiscal prudence and responsibility.
It was not that van Persie moved that surprised many fans. Rather, it was where he went.
In many sports (particularly American sports) where players are traded for one another, it is usually a bad idea to part with the best player in the deal. The lesser pieces that often come back in exchange rarely are able to fill the hole left by the departed star.
Trading a premier player to a direct rival is another no-no. Fans hate to watch an old hero come back to torment the home side.
Arsenal's sale of RVP to United, then, was a double disaster. All the Gunners had to show for van Persie's departure was a pile of the Glazers' money.
Meanwhile, van Persie has relentlessly piled up goals for a United side that leads the Premiership comfortably. In other words, all those goals van Persie has scored for United (he leads the league with 16, one ahead of Luis Suarez) have helped the Red Devils push Arsenal further down the table.
On the "Men in Blazers" podcast on Grantland.com, Michael Davies recently observed that van Persie's incandescent form for United calls into question how renowned offensive genius Arsene Wenger failed to win any silverware while van Persie was a Gunner.
The talent surrounding van Persie at Old Trafford surely has something to do with it. After all, van Persie no longer needs to tolerate Gervinho and Theo Walcott mis-timing crosses. Or, even worse, striking the ball themselves.
In truth, though, this might just be another example of Sir Alex Ferguson doing more with a player than another coach can.
Still, life at the Emirates goes on. The grand experiment of Theo Walcott as the focal point of Wenger's attack continues with moments of joy and misery in equal measure.
Walcott leads Arsenal with eight Premier League goals. He has help, though, as Santi Cazorla (seven goals) and Olivier Giroud and Lukas Podolski with six goals apiece round out a balanced, but inconsistent, attack.
Inconsistent, because Arsenal has alternated between big-goal outputs (five goals at Reading, seven at home against Newcastle) to dry spells (single tallies at much weaker sides Southampton and Wigan Athletic) in its past four matches.
Sergio Aguero will miss the match as he continues to recover from a hamstring injury.
Arsenal away, though, is quite another matter. City only managed a draw with Arsenal at the Etihad eariler this season.
In the not-so-distant past, Mario Balotelli might have been the extra weapon that Roberto Mancini would deploy in a high-stakes match like this one.
Unfortunately, Balotelli's most notable efforts in the past week have come on the training ground squabbling with Mancini. Balo did score twice this past week...for City's U21 side, per Sky Sports.
Goals will almost certainly come in this match. While neither team can afford to lose, at the rate United keeps winning, neither Arsenal nor City can much afford a draw.
Which means, naturally, that a draw is exceedingly likely.