Wigan have won 3 of their last 4 games defeating Liverpool, Stoke and Man Utd. These results were not flukes, they merited these wins. It is fair to say they dominated Man Utd, having had more possession and more shots on target (8 to 3). In addition, they were extremely unlucky to come away from Stamford Bridge with a loss after conceding two 'goals' from an offside position.
We have no choice but to play the best team we have available to us. Szczesny
Sagna - Djourou - Vermaelen - Gibbs
Arteta - Song
Walcott - Rosicky - Benayoun
Van Persie
Why have I selected Benayoun? With Benayoun coming inside off the left, it allows him and Rosicky to work short passes, form triangles with van Persie or Arteta enabling Arsenal to better control the tempo of the game and maintain possession (something teams have been struggling to do against Wigan in recent times). Sadly, I can imagine Wenger playing Ramsey on the left for much the same reasons (although Benayoun provides more of a direct threat with his dribbling abilities).
Why Gibbs? With Benayoun drifting inside, this opens up space for Gibbs to go wide and get crosses in from the byline - something that worked well against Man City. Santos, like Benayoun, likes to run into central positions and - as a consequence - Arsenal would be compromising width to play both.