Dortmund's performance against St. Pauli was good, the only thing that affected them in the match was the red card, Dortmund need to know how to defend when any of their players get a red card, leading 3-1 and ending the match 3-3 is not a good result, I said it before that Dortmund can't challenge Bayern Munich for the league title this season because Dortmund don't have the winning mentality that Bayern Munich has, Bayern Munich have more good players than Dortmund and eve if they meet this season Bayern Munich will beat Dortmund.
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Even though Dortmund had led from the start of the match and appeared dominant, unfortunately in the final minutes they conceded 2 goals, which made the score a draw. What is regrettable is that their game changed drastically when Mané received a red card in the 85th minute. In the last 10–15 minutes, they should have been more defensive and maintained full concentration, but it was quite unfortunate that St. Pauli managed to score 2 goals in the closing minutes. I agree with you that with Dortmund's current style of play and mentality, it seems difficult for them to be a serious contender for Bayern Munich.