Going out of such a big group stage — where even Belgian side Club Bruges is ahead of PSG — would set a new low for the cash-rich, Qatari-backed club. PSG's owners, QSI, have spent fortunes trying to turn PSG into a dominant European club.

Four years ago, in 2020, Bayern Munich beat Paris Saint-Germain 1-0 in the Champions League final. Tonight, they meet for the third time since. Those four years — an Olympic cycle, a World Cup cycle — is a period of time that lends itself to assessing how the two clubs, which share as many similarities as differences, have changed.