Ronald Koeman says he takes full responsibility for Saints’ second half capitulation as they suffered their biggest home defeat in 56 years in a 6-1 quarter-final thrashing by Liverpool.

An expectant St Mary’s crowd were buzzing over the prospect of reaching the last four of the League Cup for only the third time in the club’s history after Sadio Mane gave them the lead after just 39 seconds.

But the evening turned sour, with Saints trailing 3-1 by half time, and then capitulating after a change of formation from Koeman in the second period to ship six at home for the first time since 1995.

A clearly shell shocked Koeman held his hands up for a portion of the blame.

“Very disappointed,” he said after the match.

“You don’t expect a defeat of 6-1.

“I think the start on the game was fantastic but the whole team performance, and I speak about the first 45 minutes, defensive wise was not good.

“If you analyse the first goal, about a throw in of Liverpool, how easy they come out of that situation and to score the 1-1. It was already a message to everybody defensively wasn’t good.

“You know great play of Liverpool I have to recognise, they play a fantastic game, very complete, defensively strong, good movements, and they killed the game by high quality.

“But too easy in my opinion in our defensive organisation, defensive communication.

“The second half is my responsibility because I took the decision to play different, to play with three at the back.

“The first 20 minutes after half time I think it was a little bit better but we didn’t score the 2-3 and the last 20 minutes is my responsibility.

“Too big spaces, too big gaps for them, and again great quality of them to score the goals in the last part of the game.

“That’s in my opinion what happened.”

Saints went into the game having suffered back-to-back defeats to Stoke and Manchester City, but this was the kind of result Koeman had not previously experienced as manager.

“Ok, you know if the confidence in the team is not that high what you need to have a good result, if in the last 20 minutes it’s too open, too offensively, they can kill but that’s my responsibility because that’s what I like to do to have a risk,” he reflected.

“You know, I understand, and the comeback in the game.

“It’s not a case of losing the game 5-1, 6-1, 3-1, we are out of the tournament and that was the reason to change the system.”