In fact, Sevilla's performance was good but not well enough to beat a strong team like Manchester United, they focused on this match because the Europa League in their only hope but I think the reason why they won the game was the bad performance of Manchester United against them that's why if Juventus don't do the same mistake they won't have a hard day against Sevilla.
I think Juventus are well aware of that at this point because they are already in the semifinals of the Europa League this season so it will be very detrimental if Juventus are not focused and consistent to win and go to the final. Because if for example Juventus can make it to the Europa League final this season, Juventus will also not face such a strong team in the final because AS Roma and Leverkusen are also teams whose performances have been mediocre this season.
Even though Juventus made it to the semifinals, that doesn't mean Juventus have the good ability to reach the final and win the title, because in reality so far this season Juventus has looked very unstable so that the chance for Juventus to reach the final and win the title remains a low chance.
Besides that, I don't agree when you say Bayer Leverkusen have had a mediocre performance this season. Because Bayer Leverkusen made a very extraordinary improvement in the Bundesliga and also in the Europa League of course and because of that, Bayer Leverkusen also has a good chance to reach the final and also a good chance to win the Europa League title this season.