A win for the Bavarians would take last season's beaten finalists through to the last 16 with a game to spare, while victory for Valencia without conceding - or by more than a single goal - would guarantee them one of the two qualifying berths and leave Bayern sweating.
A draw, on the other hand, would only serve to do Bayern a favour, being enough to see them through if BATE Borisov slip up against Lille, but the Germans are focusing on getting all three points tomorrow night.
"We want to win the group," said chairman Karl-Heinz Rummenigge prior to departure.
Mario Gomez, who scored 12 goals in last season's Champions League, has yet to play in the competition this term due to an ankle injury, but is now ready for his comeback.
Franck Ribery is also due to feature against Valencia after missing the weekend's draw with Nurnberg, but Arjen Robben is back on the sidelines with a torn muscle and Luiz Gustavo has had groin surgery.
Valencia have won their last seven competitive matches at the Mestalla, including Champions League triumphs over BATE and Lille, while they have only lost once in 15 games in front of their own fans since March.
"It's a very important game for the club and the fans, but we're ready to have a good game," said defender Adil Rami.
"We know that they are one of the best teams in the world, but we shouldn't forget that at home we're looking unbeatable. Here we have our best weapons."
The hosts will be without Fernando Gago and Joao Pereira, with both players sidelined due to calf injuries, and Jeremy Mathieu is a long-term absentee due to problems with his Achilles tendons.
However, defender Ricardo Costa and Aly Cissokho are available after sitting out the weekend win over Espanyol in La Liga due to a virus and suspension respectively.