Steven Gerrard could barely believe it, and neither could the Anfield crowd or millions watching around the world.
Yet when the replay was screened of the Liverpool captain stamping on Manchester United midfielder Ander Herrera, it was clear his instant red card was deserved.
It was a huge call from the referee to send off the skipper, just 38 seconds after coming on as a second half substitute.
Gerrard would later apologise to his Liverpool teammates and supporters, reported by the BBC, although notably not to Herrera.
United won the game 2-1 thanks to a superb brace from Juan Mata. Daniel Sturridge pulled one back for Liverpool, with Wayne Rooney missing a late penalty.
As it stands it is set to be Gerrard's last game against United, with him set to depart Liverpool in the summer to join MLS side LA Galaxy.
He could not have foreseen it would end in such a terrible way, but for United fans it was comedy gold to see the Liverpool captain who they love to deride, lose his head and pick up an instant red card in such an important game.
Here are more photos for United supporters to savour of Gerrard's red card...