Trailing 2-0, the Skyblues provided the essentials against the RBL (3-2).
Already qualified, Manchester City and Leipzig competed for first place in the group, with the Germans aiming to win by three goals at the Etihad Stadium.
The feat took shape in the first period, with the double from former Lensois Loïs Openda, on two dazzling counterattacks (13th, 33rd). But Man City turned things around in the second half, with goals from Erling Haaland (55th), Phil Foden (70th) and Julian Alvarez (87th).
Everything is decided in this group, where City will finish first, ahead of Leipzig. Winners of Red Star (2-0), Young Boys will take third place, synonymous with a ticket for the Europa League play-offs.