The 20-time English champions led 2-0 and 3-1 in Turkey but were ultimately made to settle for a share of the spoils, with their hopes of reaching the round of 16 now hanging by a thread.
In order to advance to the next stage, Man United must beat already-qualified Bayern Munich in their final match in the section and hope that Copenhagen and Galatasaray play out a draw.
Ten Hag was prepared to take the blame for his side's latest capitulation in the Champions League, but he said that everyone, including the coaching staff and the players, must learn lessons from the match.
Andre Onana's role in the result has again been criticised, with the Man United goalkeeper allowing two tame free-kicks from Hakim Ziyech to find the back of the net.
The Cameroonian's position for Galatasaray's third has also been questioned despite the fact that it was an explosive strike from Kerem Akturkoglu.
«I think every goal has its own story. The first is a transition moment, when you speak about quick release, we don't block the middle,» he told reporters after the clash in Istanbul.
«The second is a free-kick, an unnecessary free-kick, but then we have to defend the free-kick better and then the third one, we are very good and organised but we got run off and we are in an overload area.
»So it can never happen, these mistakes can't be. In the Champions League, you get punished for it, so you have to learn from it.
«We were winning and then we're losing [points]. We should have taken three points, clear. That is also [the case] in more games: at home against Galatasaray,
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