The experienced coach is eagerly anticipating the clash with Sir Alex Ferguson's side and is hopeful the Istanbul club can get a positive result
The Turkish champions currently sit second in Group H with four points from as many games, and they desperately need a good result against United in order to keep their chances of reaching the round of 16 alive.
"It's clear that this match is one of the most important games in Galatasaray's history," Terim stated at a press conference.
"Hopefully we'll see a historic night at the Ali Sami Yen. I am sure that the fans will be putting a lot of effort into their preparations for the game and will support us until the final whistle.
"Our group is very complicated. There are two teams on four points and one team with three. The best thing now is us and Cluj winning tomorrow. That will give us a great advantage if no guarantees."
United will be without several first team regulars against Gala, but Terim has stressed that they are still a force to be reckoned with.
"I don't understand why the media are focusing on Manchester United's Istanbul squad. We shouldn't dwell too much on it because it's still United that you're facing in the end. They are one of the best teams in Europe."