Bayern are aiming to complete a stunning treble following their post-shutdown romp to the Bundesliga and DFB-Pokal titles.
The German champions are well placed to reach the final eight-team mini-tournament in Lisbon as they lead Chelsea 3-0 heading into the home leg of their last-16 tie.
But Bayern have not played since the Pokal final against Bayer Leverkusen on July 4 and so have organised an exhibition match against Marseille at the FC Bayern Campus. They then face Chelsea on August 8.
Head coach Hansi Flick said: "The 'Audi Football Summit' against Olympique Marseille comes at an optimal time in our preparations for the second leg of the Champions League round of 16 against Chelsea.
"The team and our coaching staff will be working with great focus and high quality to make sure we pick up where we left off with our performances in the Bundesliga and the DFB-Pokal final in this game."
Marseille are preparing for the 2020-21 Ligue 1 season after the previous campaign was curtailed due to coronavirus.