After four games, Bayern have lost twice -- including a 4-1 defeat by Barcelona, led by their former boss Hansi Flick -- and sit 17th, which would leave them unseeded for the knockout phase play-off.
PSG's situation is even worse, with the French champions in 25th -- one spot outside the knockout places entirely.
For two teams who contested the Champions League final just four years ago, and who both lead their leagues by six points, the lowly rankings are already cause for concern.
Bayern's struggles are a far cry from their exploits in the old group stage, where the six-time European champions signed off with a record 40-match unbeaten run, featuring 36 wins and four draws.
Their last loss in the group phase came back in 2017 -- a 3-0 defeat to Tuesday's opponents PSG.
This season, other than Bayern's loss in Barcelona, which led to whispers new coach Vincent Kompany may struggle against top sides, the German giants have impressed.
Unbeaten in the league, Bayern's only other defeat came in the Champions League away at Aston Villa -- a 1-0 loss in a repeat of the 1982 European Cup final.
As it would be for PSG, a league phase elimination remains an unthinkable possibility -- and one which could have real ramifications for Kompany.
The crowded football calendar provides a real incentive for finishing in the top eight and avoiding the extra play-off round for teams finishing from ninth to 24th.
Thomas Mueller knows PSG, who still have to play Manchester City, will be eager to gain ground after an underwhelming start in Europe.
"Paris' position in the table does not reflect their performance. They're a super team with super individual players," the Bayern veteran told BR24 on Saturday.
"A lot is at stake. I'm happy it's at home."
'Married couple'
PSG's loss to Bayern in the 2020 final -- when their former academy product Kingsley Coman scored the winner against them -- remains the closest the French side have come to Champions League glory.
Collectively, Bayern and PSG have won 21 of the past 24 league titles on offer at home, and the two have made a habit of running into each other in Europe.
Tuesday's meeting marks the fourth time in six seasons the pair will meet. Bayern have won four of the five past games but PSG did eliminate them in the quarter-finals of the 2020-21 competition.
"In the Champions League, you almost feel we're a married couple," Bayern CEO Jan-Christian Dreesen said earlier this year after the draw was made.
PSG's swift attackers will hope to trouble a Bayern side missing defensive midfielders Aleksandar Pavlovic and Joao Palhinha.
The out-of-form Leon Goretzka deputised well in Friday's 3-0 home win over Augsburg, but PSG are likely to pose a different level of threat.
Bayern defender Dayot Upamecano is better placed than most to know what to expect from France team-mates Ousmane Dembele and Bradley Barcola.
"It's an important game for us," Upamecano told Telefoot on Sunday.
"If you look at the table, it's not great -- we are not where we want to be."
