SCOTT BROWN has insisted Celtic’s 7-0 defeat at the hands of Barcelona was “unacceptable” and blamed his team’s second-half defensive meltdown for what was a record European defeat for the club.

None of the players sought to hide from any embarrassment they felt in the aftermath of a sobering night in the Nou Camp, even if a Lionel Messi inspired Barcelona produced a performance that would have given any team in the world major problems.

For Brown, and many of his team-mates, losing to such a wonderful side was no shame but the way Celtic capitulated in the second-half when they lost five goals, a figure which could easily have been more, was what severely irked the midfielder who has had far better nights against the Catalans in the Champions League.

Read more: Scott Sinclair was left battered, bruised and bewildered after Celtic's football lesson by BarcelonaThe Herald: Praying for a result: Scott Brown and Celtic face a showdown with the mighty Barcelona on Tuesday night (Picture: SNS)

“I think if you look back on the first half, we’ve defended really well,” said Brown who was one of the few to get pass marks. “They scored a very early goal – a great finish by Messi – but we almost managed to get ourselves back into the game, we missed a penalty and Scott Sinclair had a goal disallowed for offside.

“But second half we let ourselves down and five goals in 45 minutes is not good enough for anyone. To come here, and I know they’re a great team who will always create chances and score goals, we need to be better as a team. We need to defend better, from the front all the way back.

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“I do think it’s unacceptable. We’ve been here before and got beat 2-1, 1-0 and there’s also been a 6-1. But the way we played, it’s not our best performance and we’ve let ourselves down. I think the main thing is we watch the video back and see how we can be better as a team, defending and everything else. We also have to be a lot better on the ball.

“We’ve definitely gone from a high to a low in just two or three days. It’s not acceptable. We’ve sat down and talked about it in the changing room. But, we need to deal with that now, we need to kick on and get a result at Inverness. Then we’ve got Manchester City in a couple of weeks.”

The Celtic supporters situated in the top tier of the Nou Camp and those watching through their fingers at home have been reluctant to criticise their team too much given the world class abilities of their opposition.

Brown, however, still believed the Scottish champions should never concede seven goals no matter how difficult the situation.

“I know Barcelona are a great team and they’re going to press you. They are always going to create and score goals,” said Brown. “But we can’t just write it a result like this off because of how good Barcelona are. We’re in a hard group and if we think like that already then we’re not going to score any goals or win any games."

“We need to start thinking and focus a lot better during the games and work harder as a team on and off the park.”

Brown hinted that some harsh words were said at half-time and said: “What happens in the dressing room stays in the dressing room. That’s all I‘m saying.”

He also pledged that Celtic would recover and get better as he looked ahead to the remaining five Group C games in the Champions League.

“I definitely think there will be a reaction against Manchester City when we play them at home next,” said Brown.” We need to show that, and we know that at Celtic Park anything can happen. We’ve let ourselves down and need to respond strongly.

Read more: Scott Sinclair was left battered, bruised and bewildered after Celtic's football lesson by Barcelona

“We’ve beaten Barcelona and AC Milan before there, so here’s hoping we can focus on that and try to get three points as quickly as possible.

“I’ve never lost a game by seven. It was bad enough losing 6-1 here. But 7-0 beats anything else I’ve ever had. No one wants that kind of defeat. It’s a hard game to have happened and we should be doing better than that.”

Patrick Roberts, who enjoyed a fruitless night on the wing, was red faced after what for him was the toughest experience of his career so far.

“Going to the Nou Camp is probably one of the hardest things you will ever have to do as a footballer,” said the Englishman.

“They completely played us off the park. Seven goals, for me personally, is embarrassing. In football, you don’t want to ever get beat. Losing seven goals is always going to hurt but we will get on with it and go again.

“We deserved to get to the Champions League. We earned that. But we didn’t do it in Barcelona.”