"My boys have to dare and imagine that we can also win in Munich," said coach Thomas Tuchel, the youngest coach of the league at 37.
"If you do not dare think about it then you will never achieve it."
Mainz top the standings on 15 points, two ahead of Borussia Dortmund. They could be forgiven for thinking big having scored 12 goals, the second best in the league, while conceding only four.
Tuchel took over when Mainz sacked their coach Jorn Andersen days before the 2009/10 season started and already has a win against Bayern under his belt, beating them 2-1 last season.
The former Mainz U-19 coach has learned to swim very quickly after being thrown in the deep end.
While lacking the big names of Bayern, Tuchel has cleverly made the most of his resources and drawn praise for his tactical acumen.
"Our game is very similar to the English style of play," Tuchel said after their 2-0 victory over Cologne on Tuesday. "Huge power, ready to run, pressing and ball possession."
Their last league defeat stretches back to April.
Apart from long-injured Arjen Robben, Bayern will also be without Franck Ribery who tore an ankle ligament in their 2-1 win over Hoffenheim on Tuesday.
Coach Louis van Gaal will be hoping his offence will finally fire after they scored two against Hoffenheim, having managed only four goals in five Bundesliga matches so far.
Dortmund, on a four-match winning streak following their 5-0 demolition of Kaiserslautern, travel to St Pauli while third-placed Hoffenheim take on Cologne.
Last season's runners-up Schalke 04 will hope victory at home against visitors Borussia Moenchengladbach will help them climb out of bottom spot after their first win on Wednesday following four straight defeats.
