Jamie Redknapp says Steven Gerrard can only blame himself for his red card at Anfield.
The Liverpool captain was sent off under a minute after coming on as a half-time substitute, for an ill-advised stamp on United midfielder Ander Herrera.
Redknapp believes the occasion of the game must have caused the retired England captain to lose his head, but said ultimately it is his responsibility.
He said: "It was a game for cool heads and that’s what Mata had. It’s a shame the same can’t be said for Steven Gerrard.
"Watching on, he will have been at boiling point. He must have been wondering why he was on the bench when players not in his class were struggling to make an impact on the pitch. But even though I have some sympathy, that’s still no excuse."
Gerrard, speaking to the BBC, later apologised to his manager, teammates and supporters for his recklessness, although not to Herrera.
Despite his sending off, Liverpool rallied in the second half, and were still pushing for an equaliser after Wayne Rooney's late penalty miss.
A draw would really have been undeserved though, with United good value for their win, courtesy of two excellent goals from Spanish playmaker Juan Mata.
The match was Gerrard's last against United as it stands, with the Liverpool skipper set to leave at the end of the season to sign in July with MLS side LA Galaxy, as the BBC confirmed earlier this year.