The former Oasis singer stormed out of Real Madrid's Santiago Bernabeu Stadium during the second half — before the flurry of goals that hit near the end of the game, according to the Mail.
Gallagher, arguably City's most famous fan, was in attendance at what was considered the most glamorous matchup of the UEFA Champions League group stage.
Edin Dzeko gave City an improbable lead in the 69th minute, and that's when Gallagher sprang into action.
He hopped out of his seat in celebration, running up the aisle, singing, chanting and generally having a good time. The Madrid faithful didn't seem to mind at all. It's actually's unclear whether or not they recognized the rock star. Eventually, a police officer told Gallagher to get back to his seat, and he obliged.
But he wouldn't stay there for long. The Mail reports Gallagher was so upset when Marcelo tied the game in the 76th minute that he left the stadium with his buddies.
That decision caused him to miss the thrilling finale, which featured three more goals. Once again, City took and lost the lead, before Cristiano Ronaldo put Real Madrid ahead for good.
Maybe Gallagher was the inspiration behind City goalkeeper Joe Hart's stinging critique of City's performance?
Watch Gallagher's Bernabeu antics in the video below.
Photo via Twitter/@CasualMind_