I think it's
without away goals rule, so ANY 1-goal defeat would mean a square result and the following criteria would have to be checked:
Current original UEFA CL rules from August 2022:
https://documents.uefa.com/r/Regula...icle-17-Equality-of-points-group-stage-Online
Article 17 Equality of points – group stage:
17.01
If two or more teams are equal on points on completion of the group matches, the following criteria are applied
in the order given to determine their rankings:
- higher number of points obtained in the group matches played among the teams in question;
- superior goal difference from the group matches played among the teams in question;
- higher number of goals scored in the group matches played among the teams in question;
- if, after having applied criteria a) to c), teams still have an equal ranking, criteria a) to c) are reapplied exclusively to the matches between the remaining teams to determine their final rankings. If this procedure does not lead to a decision, criteria e) to k) apply in the order given to the two or more teams still equal;
- superior goal difference in all group matches;
- higher number of goals scored in all group matches;
- higher number of away goals scored in all group matches;
- higher number of wins in all group matches;
- higher number of away wins in all group matches;
- lower disciplinary points total based only on yellow and red cards received by players and team officials in all group matches (red card = 3 points, yellow card = 1 point, expulsion for two yellow cards in one match = 3 points);
- higher club coefficient (see Annex D).
In the actual club coefficient
City is ranked #1, Dortmund #14:
https://www.uefa.com/nationalassociations/uefarankings/club/#/yr/2023
Bottom line:
City win or draw -> City win the group.
BvB win by more than 1 goal -> City would need more points from the 6th matchday than BvB to win the group.
City lose by 1 goal -> criteria 5.) downwards will decide group winner.