We will see at the opening match of the EPL. Two clubs who made significant signings in the summer transfer window will meet. While the first match isn't the final, we'll still get to see what kind of play United will have to show to their fans with their new signings. The same goes for Arteta's squad, which this season has made the most transfers budget in the last 10 seasons (CMIIW).
Both clubs have recruited some of the best players, but upon closer inspection, Arsenal should win the first leg.
However, Ruben Amorim won't let his reputation be tarnished by his summer transfers and will try to put pressure on Arsenal.
The prediction is that the first leg could end in a draw, given that it will be played at Manchester United's home ground.