Bayern Munich is clearly favourite for the home game against Lazio but still this is not guaranteed because their home performance is also not good, and they are facing unknown issues which are giving them setbacks in this season, and they are now trailing in Bundesliga by 10 points which happen after decades Lazio is surely not strong team and can face problems in their coming game but still things are never been easy for the Bayern Munich because they are having bad run and their players which are looking tired are fail to give their best in last many games.
No guarantee definitely as when the season starts, people assume Bayern Munich will easily win Bundesliga after having Harry Kane from Tottenham Hotspur and they actually began this season very well. Unfortunately the season is long and problems appeared, Bayern Munich now fell behind Leverkusen with big difference enough to assume Leverkusen nearly touch one of their hands on Bundesliga title.
In the match with Lazio, Bayern Munich are stronger but I agree with you that no guarantee that Bayern Munich will beat this opponent and be a next team qualified for quarter finals.
But expectations are still high for their win in coming game because Lazio is also suffering into their last few games and their performance is also on decline which is surely not good deal for them before this big game which is coming in few days they needed to be at their best again if they are looking for the another win here in Germany after winning their first game at home.
They are an Italian team and they actually master Catenaccio which will be used in Munich. They don't need to win in Munich, a draw is enough for Lazio and they will use Catenaccio defensive art of Italian football to prevent Bayern Munich scoring goals and beat them.