Last season when United performance was poor in EPL matches, Arsenal was unable to win United easily during their clash. This week Sunday will prove to us, if United performance has improved or not when the meet with Arsenal. Arsenal is in a good form than United and I expect them to win the match.
The first match will be very difficult to predict, but the Manchester United vs. Arsenal match will be the same. This won't be easy for either team. Although Arsenal currently appears to be stronger, Manchester United remains a top Premier League team and must be reckoned with. This is a prestigious match for both teams.
Manchester United will be playing at home, and in their first few matches of the season, they have struggled to lose, so I predict the same, especially since Manchester United, playing at home, will certainly have much higher motivation.