Yes, this match is very difficult to predict. Arsenal is far ahead in terms of team strength. Since Manchester United will be playing at home and have signed some new players in the team, it would be very foolish to ignore Manchester United. Arsenal also knows that and they will try to take the first win of the season seriously in the first match of the season. Manchester United's big strength in the match will be the support of the audience, they will definitely try to taste the first win of the season with that strength by creating a great competition against Arsenal. I will not make any predictions now, I will wait for a great fight.
Arsenal does appear far ahead of Manchester United in team strength and quality but I still do not get convinced about the chances of this particular game turning out an easy one in favour of Arsenal, it is the first game of the season and it will come with a lot of mixed feelings for both team but Arsenal appear la to be the favourite to many but I am going to watch this game without expectations because that is the best way I figured I can enjoy the game the most.
This certainly won't be an easy match for Arsenal, even though they are favored in the opening match against Manchester United. The match will be played at Old Trafford, Manchester United's home ground, making things a bit difficult for Arsenal.
Arsenal have a slightly better chance of winning, but the match will likely be very close, so I think there's a good chance of a draw.