UEFA have postponed all this week's remaining Champions League and UEFA Cup ties as a "mark of respect" to the victims of yesterday's terrorist attacks in the United States.
There was due to be a full schedule of ties in the Champions League tonight and the UEFA Cup on Thursday which involved both English and Scottish clubs.
Manchester United were in Greece to take on Olympiakos, while Celtic were playing Rosenborg tonight.
Tomorrow's UEFA Cup games should have seen Leeds play Maritimo in Madeira, while Chelsea, Ipswich, Aston Villa and Kilmarnock all had home ties.
Hibernian were playing AEK Athens in the Greek capital, while Rangers were supposed to be playing Anzhi Makhachkala in Dagestan - although chairman David Murray had already pulled his players out of the game over safety fears in the war-torn Russian republic.
"The scale of this tragedy and the pain and sorrow which it brings should cause us all to reflect," said UEFA chief executive Gerhard Aigner in a statement.
"UEFA feels it is right that the European football family should respect the loss and suffering now being felt by those families who have lost their loved ones by postponing all UEFA games scheduled to be played this week.
"On behalf of UEFA I would like to send our condolences and deepest sympathies to all those who are in pain as a result of these terrible events.
"We will convey this in a formal message to the US Embassy in Geneva.
"We will continue to monitor the overall security situation within Europe over the next few days and will make further statement in due course concerning the rescheduling of these games."
English football will continue as planned this weekend according to officials.
PA