Chelsea were knocked out of the 2009 Champions League semi-finals by Barcelona, exiting the compeititon on away goals in a 1-1 draw.
The game was not without its controversies and the Blues had numerous penalty appeals which were dismissed by referee Tom Henning Ovrebo.
The Stamford Bridge club were incensed and Michael Ballack famously chased the ref across the pitch while Didier Drogba branded him a “disgrace” in his post-match comments.
And the Norwegian official has now admitted in a candid interview with Spanish newspaper Marca that he was not proud of his performance and has apologised to the Blues.
Bizarre moment referee kicks out at player and sends him off
"It was not my best day, really," Ovrebo said.
"But those mistakes can be committed by a referee... and sometimes a player or a coach. Some days you're not at the level you should be.
"I can't be proud of that performance. They were handball situations.
“I judged them on the pitch and I think it is not interesting to know what I think of those actions once judged.
“But I understand that people think differently to the decisions I made at the time. That discussion will continue eternally.
"I was responsible for the decisions that were made and we can argue that, if I had taken others, maybe Chelsea would have qualified for the final.
"We will never know. I made decisions and they were not the best.
“But it is difficult to say if, without that arbitration, Barcelona would have been eliminated or not."