Steven Gerrard
Gerrard's last game against United as a Liverpool player ended in disgrace (Getty)

Steven Gerrard has apologised following his sending off in Liverpool's 2-1 defeat to Manchester United, saying he doesn't know what caused his moment of madness.

The Reds captain came off the substitutes' bench at the start of the second half but lasted just 38 seconds before being shown a straight red by referee Martin Atkinson following a stamp on Ander Herrera.

United scored their second goal of their afternoon soon after the incident and despite Liverpool pulling a goal back through Daniel Sturridge, went on to lose their first game since December.

After the match, Gerrard acknowledged he had made a mistake and was quick to apologise to supporters.

"I need to accept it, I think the decision was right," he said. "I've let my teammates and the manager down today, and even more importantly let all of the supporters down.

"I take full responsibility for my action. I've tried to jump his tackle when I've seen his studs and I've reacted wrong.

"I've been in the game long enough to know when you do something like that… especially with the timing of the game – 45 to play with a great opportunity to get back into the game. I take full responsibility for it."

"I don't know [what caused it]. It was probably just a reaction to the initial tackle, but I don't think I should say too much more on it, really.

"I've come to speak to apologise to everyone in the dressing room and all of the supporters all over the place, because I take full responsibility for today's result."

Juan Mata opened the scoring for United after just 14 minutes, sweeping home an excellent through ball from his countryman Ander Herrera.

United proceeded to dominate the first half, prompting Gerrard's introduction at half time.

But his swift departure allowed the visitors to keep a tight grip on the contest and Mata would double his tally for the afternoon with a wonderful scissor kick after 59 minutes.

Sturridge's effort with just over 20 minutes remaining forced United onto the back foot, but the home side were unable to trouble David de Gea in the United goal.

In extra time, Emre Can fouled Daley Blind in the box to provide United with the chance to make it three, but Wayne Rooney missed from the penalty spot.