Manchester United was highly favorite and also playing at home so how can it play as DSC.. please explain
The answer to your query is "Castle Besiegment in Sports" (Google for further articles)
If you see the group stage AZ was undefeated whereas ManUtd had lost 1 game. AZ became the Champ were in Man Utd was the challenger.
Since Sub Lords very on a grandeur level against the ASC, I expected lots of goals to come by DSC (AZ in this case) during the 2nd half. Nevertheless, Man Utd scored 4 goals back to back in an interval of 5 mins or so and AZ denied their 1 goal too.
We often talk and hear about reversals in Cricket & Soccer - Castle Besiegment is the reason for the same. A team that's on a winning streak goes against a team that has won and lost becomes the ASC for that game.
With enough Astrological knowledge & experience, you get to know this by who wins the coin Toss based on the planetary positions, sub lords etc.