Manchester United manager Sir Alex Ferguson has repeated his criticism of the weekend atmosphere inside Old Trafford.
Highlighting the contribution 6,000 Celtic fans made to one of the best atmospheres the ground has seen for years during Wednesday night's Champions League match, Ferguson claimed crowds for Saturday and Sunday fixtures contained a greater percentage of corporate supporters and those on weekend breaks.
The Manchester United boss does not envisage a problem for Sunday's visit of Arsenal and he also believes the decision to fill in the quadrants next to the massive North Stand - increasing the stadium capacity to 76,000 - has made a positive difference.
But he is aware that often, Old Trafford is far too quiet.
'There is no question Wednesday's atmosphere is what you want,' he said.
'Anyone who was there will look back at the game and say it was a special night, made so by Celtic's supporters, who never stopped getting behind their team and raised the bar for our own fans.
'Wednesday games seem to attract the real supporters, who want to come and see us every week and get right behind the team, as I am sure it will be on Sunday.
'On Saturdays, we have fans coming in from other parts of the world to admire the stadium. There are some on weekend packages and others on corporate hospitality.
'Sometimes, a sunny day at Old Trafford can be quite laid back.'