First goal is of paramount importance
In the last 10 matches between the two sides which have been won by one or another, the side that scored the first goal has gone on to win in nine of them. The last time either of the teams came back from a goal down was in 2009, after Andrey Arshavin put the Gunners one up before being cancelled out by a Wayne Rooney penalty and Abou Diaby own-goal.