It happens in the majority of stadiums these days, watching the classico in a stadium of 85 thousand during the week you can hear a pin drop and the City match yesterday was like a morgue.
The atmosphere at Celtic Park is in general decent especially as you would expect on European nights but sometimes the place can be dead with the exception of the Green Brigade (Our Ultra Group) they sing non stop for 90 mins and would dread to think of the place without them.