Sonny Bradley reflected on Pompey’s alarming defensive frailties and vowed: We won’t let it happen again.
Guy Whittingham’s side slumped to a 4-1 defeat to Oxford at Fratton Park on Saturday in their League Two opener.
The Blues had even taken a 24th-minute lead through Patrick Agyemang during a bright opening.
But misjudgments, each from full-backs Dan Butler and Yassin Moutaouakil, handed the initiative to the U’s, who went in at the break 2-1 up.
The second half saw Johnny Ertl shown a straight red card and the 10-men subsequently conceding a further two goals.
But Bradley is convinced the defence can learn from their miserable display.
He said: ‘The first two goals didn’t kill the game but we went in at half-time a little bit down.
‘If we go in 1-0 up without those defensive errors it is a completely different game.
‘You are settled down, you have a lead into the second half and something like 75 per cent of the time the game finishes 1-0.
‘Unfortunately, those defensive errors cost us.
‘There were a few fingers pointed at half-time but players know if they have made a mistake.
‘I made mistakes on Saturday, a few little individual errors, but fortunately for me it hasn’t cost us a goal.
‘Even though they are individual mistakes, we aren’t going to point our fingers at players. It doesn’t get you anywhere.
‘We will look at it as a team, sit down as a team, go through it and learn from it.
‘It’s disappointing because we know how good we are and the earlier we can cut that out of our game the quicker we can move on.
‘I think me, Yassin, Joe (Devera) and Dan are quality players and I know we are strong enough not to dwell on it because that’s the last thing we need.
‘They are strong characters so there is no reason why they won’t play tomorrow (at Bournemouth) and come out and give 10/10 performances – which I am sure they will.’
Butler and Moutaouakil were criticised by fans as Oxford hit back to go 2-1 up.
And Bradley agreed they should have defended both costly situations differently.
He added: ‘Maybe Yassin should have just kicked it out, basic defending really.
‘Even when you watch the Premier League and Championship, if that ball needs to go over the stand it goes over the stand and you get back and regroup.
‘Then again, had he brought it down, put it in the channel, we got a cross in and scored everyone would be saying he is wonderful.
‘As for Dan, taking nothing away from Alfie Potter, but maybe he went past him a little too easy.
‘But I think that’s the only time it happened.
‘Unfortunately, it cost us a goal.’