Steven Gerrard said he accepted full responsibility after being shown a red card within seconds of his introduction during Liverpool's 2-1 defeat at home to Manchester United.
Liverpool had been trailing 1-0 when Gerrard came on for Adam Lallana at half-time, but less than a minute after his introduction he had been dismissed for a stamp on Ander Herrera following a challenge with Juan Mata.
Speaking to Sky Sports after the game, which appears likely to have been his final game against United, he said: "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.
"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.''
Gerrard's former Liverpool teammate Jamie Carragher described the red card as a "moment of madness" borne out of frustration.
He said on Sky Sports: "There's no doubt that not playing at Swansea [in Liverpool's last game] and then not playing this game would be a frustration.
"He's been at Liverpool 17, 18 years, he's always been the man, the captain -- there's never been a case where he's been out of the team and as soon as he's fit he goes straight back in the team.
"This is the first time I think, last week at Swansea and, today, that hasn't happened, so there'll be frustration there.
"Watching the first half from the bench he'd have been disappointed. Liverpool weren't playing well, they were losing 1-0. But there would have been more frustration.
"I think he'd have been watching players in his position performing not great and thinking, 'Why am I not playing, why am I not on that pitch?' We said at half-time that was the right call: bring him on.
"Steven Gerrard is an emotional player. You see that in his career and it's taken teams I've played in into some unbelievable moments.
"Sometimes he hasn't played with his brain in terms of when he's done well, it's been his heart - the [2006 FA] Cup final against West Ham, Istanbul [the 2005 Champions League final]. That wasn't Steven Gerrard playing with a cold, calculated head, that was just playing from the heart. He can do special things like that.
"But on the flip side of that, when he plays in games like this and he comes on maybe a bit frustrated -- he's had seven red cards in his career, [and] four of them have been Everton and Manchester United, two each now. An Everton one was coming off the bench, an Everton one was 15, 20 minutes into a game. I think the United other one was an FA Cup game in the first half and if I think right they were all straight reds.
"There's no doubt being a local player, the emotion of these occasions, the frustration coming into this game, has contributed to the moment of madness."
He added: "It's a straight red, there's no arguments with that. You can't do that on a football pitch. He's been rightly given his marching orders."
Information from the Press Association was used in this report.