A 1-0 defeat to Borussia Dortmund means Bayern now trail the league leaders by six points with four games remaining.
That gap may have increased to nine points by the time Bayern take to the field, which is why they could be forgiven for forgetting about the league and focusing their efforts on the Champions League.
On Tuesday, they host Real Madrid in the first leg of their semi-final clash and, with the prospect of playing the final in their own stadium still very much alive, Jupp Heynckes' troops could be rotated to keep them fresh.
"It is inevitable that, with so many games, you have got to change your starting XI," Heynckes said.
"I have got to find the right balance and find a team who will beat Mainz.
"We have got to concentrate on the next game and that is Mainz, and a win is important to warm us up for Madrid."
Mario Gomez, Franck Ribery and Arjen Robben are the three likeliest candidates for a break, with Ivica Olic, Thomas Muller and Luiz Gustavo set to replace them.
There will be no breaks for any of the Mainz players, though, as their coach Thomas Tuchel has demanded 100% until the end of the season.
They beat Cologne 4-0 in midweek, but they are not yet totally out of danger.
"We have got to keep our full concentration right up until the very last game of the season," Tuchel said.
"You can only reach your goals when you keep your focus."
Only Marcel Risse and Bo Svensson are unavailable for Tuchel, who has a large squad to pick from.
