To be played on Wednesday 12th February 2014 at 19:45. Venue: Emirates Stadium, London.
All the latest ahead of the important clash...
Arsenal injury and team news
Thomas Vermaelen - Vermaelen has a calf injury but has been ruled out of the clash by Arsene Wenger. He could be in contention to feature against Liverpool in the FA Cup at the weekend.
Aaron Ramsey - Key midfielder Aaron Ramsey could have been expected to help Arsenal dominate against United, but he is likely to be out the entire month with a groin injury. A big loss.
Yaya Sanogo - Much an unknown quantity at Premier League level, Arsene Wenger has confirmed Yaya Sanogo is fit to feature, and has a chance of making the bench.
Mathieu Flamini - Flamini is suspended for this match after his red card against Southampton last month. This is the last game of his ban and he returns for the FA Cup clash at the weekend.
Kim Kallstrom - The new loan signing remains on the sidelines with a back injury, and will not feature.
Manchester United injury and team news
Marouane Fellaini - Fellaini suffered a setback in his recovery to fitness from wrist surgery last week with a groin strain, but Manchester United confirmed last night he is fit and in contention to feature against The Gunners.
Phil Jones - Jones has been recuperating from a concussion sustained in the loss to Stoke, but like Fellaini he has been ruled fit and could feature.
Tom Cleverley - The 24-year-old missed the draw with Fulham after picking up a knock in training. Unlike Fellaini and Jones, United have not announced he is fit to return and he is therefore expected to miss out.
Jonny Evans - Evans picked up a calf injury ahead of the Stoke game and has not recovered. Again likely to watch from the sidelines.
Nani - The Portuguese winger suffered a hamstring injury in training at the end of January and will be out for the rest of the month.
Rio Ferdinand - The centre-back is also ruled out with a knee injury, meaning United have three to pick from Vidic, Smalling and Jones.