Celtic's opening Champions League opponents Slovan Bratislava were forced to apologise to their own fans after a catastrophic 5-0 home defeat.
The Hoops start their campaign with a home tie against the Slovakian champions, who qualified for the group stage by beating Danish side FC Midtjylland.
But while Celtic were cruising to success against Rangers, Slovan's preparations could hardly have been worse after getting hammered at their own home ground by MSK Zilina.
Read more:
-
Celtic vs Rangers: Unseen moment Joe Hart fires up former team-mates
-
Kyogo delivers hilarious description of Celtic vs Rangers goal
Manager Vladimir Weiss was so disgusted by the performance, he refused to speak after the game, but his namesake son Vladimir - who had a loan spell at Rangers 14 years ago - admitted they were miles off it.
He said: "I would like to apologise to the fans.
"Before this match, we were full of confidence and then that happened.
"But I am not going to criticise my teammates too much. We were all heroes a few days ago. But these things happen in football.
"We know we were below average and we have to improve for all the important games coming up."