Yes, indeed many, because of that, Xabi also admitted that it will not be easy and they seem to need a miracle. And indeed as you said, Leverkusen so far also performs very well, beating Bayern Munich several times. However, here, Bayern Munich is really different this time and they seem very high motivated to win the UCL and continue to the QF round. But, yeah, we can still make some predictions again about the next match.
But as long as they still have the chance, they will struggle on it.
Even though Leverkusen has a chance in the second leg to beat Bayern Munich but they have to catch up on the goal difference which might be difficult to do. Bayern Munich's performance is much better than Leverkusen's this season so they need to work hard to be able to beat Bayern Munich in the Champions League. Xabi Alonso has shown his skill in building a squad but it will be difficult for them this season because Bayern is stronger and very motivated in every match in the Champions League.
In the Bundesliga, Bayern's performance is also better this season, especially since they were able to close the gap in their weaknesses which made Kompany succeed in bringing Bayern Munich to lead the standings for a long time. Harry Kane also contributed a lot to the team because he was very active in scoring goals and always troubled the opponent's defense. Leverkusen has a big grudge against Bayern Munich so the second leg will be more exciting than the first leg.