The visitors, meanwhile, are looking to avoid becoming stranded in the automatic relegation places.
2020 was a glorious year for Bayern, who won the Champions League, Bundesliga and German cup treble, but Hansi Flick will not allow his players to rest on their laurels.
His side ended 2020 in some style, with a last-minute Robert Lewandowski winner securing a crucial 2-1 win at Bayer Leverkusen, who had entered the clash top of the Bundesliga after the Bavarians had surprisingly drawn three of their previous five league games.
Patrik Schick had given Leverkusen an early lead with a superb volley from the edge of the area after a nicely-worked short corner, but Lewandowski pounced on a Lukas Hradecky error to nod home at the back post and level proceedings heading into the half-time interval.
There was little to separate the two sides in the second half, with Hradecky redeeming himself with a good save to deny Serge Gnabry and Jamal Musiala striking the post from distance, but Lewandowski showed precisely why he was undoubtedly the best player in the world in 2020 by sealing the victory with a deflected effort after Jonathan Tah had carelessly given the ball away in his own defensive third.
With none of Bayern's next 10 league opponents currently featuring in the top seven places in the table, Flick will sense an opportunity to open up a sizeable gap at the top of the table as the club look to win their ninth successive league title.
Mainz, meanwhile, have won just one of their opening 13 games this season as they languish second from bottom and five points from safety.
Having already sacked Achim Beierlorzer earlier in the campaign, the club have also departed with Jan-Moritz Lichte over the Christmas period as they look to find the solutions to their struggling form and survive. Former Huddersfield Town manager Jan Siewert has been handed the reins in an interim capacity.
Much of their hopes will depend on Jean-Philippe Mateta continuing his superb goalscoring form, having bagged seven league goals in 12 starts this season, with more expected from last season's top goalscorer Robert Quaison.
Mainz certainly cannot afford too many more defeats in the nature of the 1-0 home defeat to Werder Bremen prior to the winter break, with teenage debutant Eren Sami Dinkci afforded too much freedom in the penalty area when scoring a last-minute winner.
Bayern Munich Bundesliga form: DWDDWW
Bayern Munich form (all competitions): DDWDWW
Mainz 05 Bundesliga form: WDLLDL
Mainz 05 form (all competitions): DLLDLL
Siewert could welcome midfielder Levin Oztunali back to the matchday squad, with seemingly no injury concerns for Mainz to contend with.
Quaison and Mateta may be paired in attack, with the former Huddersfield boss likely to deploy a counter-attacking strategy against Bayern's high defensive line.
Bayern Munich possible starting lineup:
Neuer; Sule, Boateng, Alaba, Davies; Kimmich, Goretzka; Gnabry, Muller, Coman; Lewandowski
Mainz 05 possible starting lineup:
Zentner; Fernandes, St Juste, Hack, Niakhate, Brosinski; Barreiro, Kunde, Boetius; Quaison, Mateta
We say: Bayern Munich 4-0 Mainz 05
We can envisage Bayern kicking off the New Year with something of a rout as they look to lay a marker at the top of the table.
Managerless Mainz look to be in disarray at the moment and while Quaison and Mateta may cause problems for Bayern on the break, we do not think they will be able to handle Bayern's offensive weapons.