The Reds were already one goal down, when Gerrard replaced Adam Lallana at half-time. But he was soon off the pitch, after Martin Atkinson showed him a red card for stamping on Ander Herrera.
“I need to accept it. The decision was right. I have let my teammates and manager down today – even more importantly I let all the supporters down and I take full responsibility for my action,” he told Sky Sports.
“I tried to jump his tackle, I saw his studs and I reacted wrong. I’ve been in the game long enough to know when you do something like that, especially at the timing of the game, at half-time with 45 to play, a great opportunity to get back in the game … I take full responsibility for it.”
Asked what caused him to react that way, he said: “I don’t know. [It was] probably just a reaction to the initial tackle.
“I don’t really think I should say too much more on it. I came to speak to apologise to everyone in the dressing room, all the supporters, all the players because I take full responsibility for today’s result.”
Juan Mata scored twice as United won 2-1, to establish a five-point lead over their rivals.