The tougher match is the Bayern-Leipzig match. Leipzig is one of the teams in the league that tries to stand toe to toe with Bayern even if Bayern wins most of the time. It is very possible that Bayern can drop points against Leipzig, but I don't think will. Bayern have worked hard to be at the top of the table. They have 0vercome many struggles like inconsistency and other in team crisis, they are not going to throw this opportunity away.
And even if Bayern drops point against Leipzig, I cant be certain Dortmund can win all their matches. I hope they do but I don't trust them. So I see Bayern remaining at the top till the end of the season.
For Bayern this will be an important match and Leipzig is able to take away points from Bayern, but for Bayern this match will be more important than for Leipzig, since the title will be at stake, and Leipzig will most likely be able to finish the season in the Champions League zone, even if they lose. Dortmund do not have such difficult opponents, but Bochum did not seem to be an invincible team, and Dortmund drew with them. Tuchel also understands the importance of this victory, otherwise it will be a very bad start to his work at the club.