City have failed to win in six matches, a shocking first for manager Pep Guardiola.
City were 3-0 up in the Champions League group stages against Feyenoord at home, only to contrive to draw 3-3.
After the match, Gundogan said: "So quickly after the game I don't have the answers.
"The goals we conceded are inexplicable, in terms of the way we conceded them.
"There is only ourselves to blame. The situation, I don't know, the way things are going right now, it is a bit inexplicable."
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