It is so funny to see how things doesn't last forever, look at Leverkusen who won the league unbeaten have gotten their first defeat since last season till the season by Leipzig. This shows that they might not be able to defend the title and a different club might win the league this season. If it happens so, it means that Bundesliga is becoming unpredictable.
Leverkusen has a lot of challenges this season because they will be playing in UCL which might be a distraction to them from staying focus on winning Bundesliga this season.
Defending the record or champion status will be always harder. I think it is not a funny thing, it is something normal. There should be some changes in Leverkusen and other teams in Bundesliga. Moreover, it is Leipzig, it is one of strong teams in Bundesliga. But what makes it interesting that Leverkusen got a defeat at their own stadium. It must be a severe lose although it won't determine how the performance of Leverkusen in the next matches. Fans and Leverkusen management must expect to get full points at home, sadly Leverkusen got a defeat for the first time in this season. However, the chance to win Bundesliga is still very open for Leverkusen, there are still too many matches left.
Yes, Leverkusen has many challenges. They are demanded to defend their champion status. They are also expected to perform well in UCL. Xabi Alonso should have prepared anything for Leverkusen. But it may not be easy for Leverkusen, especially playing in UCL. The level of UCL is above UEL, Leverkusen will face many strong teams there.