What Xabi Alonso and his team have been doing in the Bundesliga is very extraordinary and unimaginable. He has beaten multiple records in the Bundesliga by being unbeaten for so long. But I would agree with @Iranus. Bayern Munich are still the favorites to win this title. There will be a time when Bayer Leverkusen will drop points Bayern Munich will get some points to get ahead of them. But I think the match that will have the most impact on this championship title race is the match between Bayern Munich and Bayer Leverkusen. Whoever wins this match will get a good advantage, even if it is 1 point. I mean 1 point is a lot considering how the current race is going. Bayern Munich knows how to gain back their lead I believe.
Xabi Alonso is the frontrunner for Leverkusen and they wouldn't handle top actions without his presence in the club. Bayern Munich are behind Bayer Leverkusen but it doesn't mean they're not able to stack up winning points closer to Leverkusen on the league table. I don't know how Bayern Munich will do it but they always managed a way to pull strings whenever it comes to Bundesliga matches. Watching Bayer Leverkusen topping the table for this long time, I think they also have 50/50 chances as Bayern Munich, it's not an isolated fight for Munich alone, rather its a tough fight for Leverkusen also.
Xabi Alonso helped Leverkusen to reach what they could never reach in the other season and with all the other coaches and if I'm not wrong Leverkusen is making history with their coach, Xabi Alonso because so far even after racing this team like Bayern Munich they had perfect performance and they are still unbeaten.
Maybe the most important thing they should do in Leverkusen is to try extending the offer of Xabi Alonso to keep him for a longer time.