The Turkish Super Lig giants came from behind to draw 3-3 with the Red Devils in the Champions League on Wednesday night.
Meanwhile, Erik ten Hag's side have been left with it all to do after dropping points from a winning position once again, with United now needing to beat Bayern and hoping Galatasaray draw with FC Copenhagen to stay in the competition.
But now, eagle-eyed fans are noticing that Galatasaray's first goal shouldn't have counted.
Former Chelsea player Hakim Ziyech scored a low free-kick on the edge of the box on the right-hand side and beat Andre Onana - who struggled on the night - to find the back of the net and make it 2-1.
It wasn't Ziyech's taking of the set-piece that was the issue though - it was the Galatasaray players in the box.
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Man United had five players lined up in a wall inside the area to try to guard Onana and stop Ziyech from finding the back of the net.
The rules state that if three or more defending players form a wall, all attacking players must remain at least one metre from the wall until the ball is played.
However, two of Galatasaray's stars were not one metre away before the ball was played and were in fact stood in the wall itself.
Ziyech's free-kick got through the gap in the wall that the Galatasaray players were stood round, too, but the goal stood nevertheless.
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After the home side halved the deficit following Alejandro Garnacho and Bruno Fernandes' openers, Man United went 3-1 up through Scott McTominay in the second half.
But a second goal from Ziyech just seven minutes later and 71st minute equaliser from Muhammed Akturkoglu saw the sides share the spoils.
Man United will now need to try to scrape themselves off the bottom of Group A in hope of keeping their Champions League dreams alive.