Seville can be said to be lucky, because when they faced Manchester United, their opponents did not play well, and even Manchester United's defense could not be relied on at all. The majority of the goals that Sevilla scored were the result of mistakes made by Manchester United players, even in the first leg 2 of Sevilla's goals were own goals created by Harry Maguire and Tyrell Malacia. And in the second leg, the Manchester United defender contributed to the goals scored by Sevilla. I honestly laughed when I saw how the Manchester United defender worked.
This is what I said to many people about those two games. It wasn't Sevilla that won those games, it was United that lost it and that is the issue, I have to say that it is purely unlucky and it was obvious from the start that if United didn't made those mistakes, they would have won very easily, it was terrible mistakes after mistakes that caused them to lose and that is not going to be Sevillas talent.
However, we need to remember that they have been playing better recently as well, not only they won their last 2 matchups at Europa, but they started to win more at la liga and went up in places a bit as well. Which doesn't mean they will win this matchup, but it means they are not as bad as they used to be at the start of the season neither.