Steve Cotterill surveyed Pompey’s new-found defensive steel and warned: I’m still not satisfied.
It has been 326 minutes since the Blues last conceded a goal.
That was when Steve Davies netted for Derby in the first half of the 1-1 Fratton Park draw at the start of this month.
Since then, Cotterill’s reshuffled defence have chalked up three successive clean sheets.
Ritchie de Laet, Greg Halford, Ricardo Rocha and Hermann Hreidarsson, coupled with keeper Jamie Ashdown, have suddenly created the defensive resilience the Blues have been desperately seeking.
They will once again be fighting alongside each other in tomorrow’s tough trip to Ipswich.
But despite their impressive displays, Cotterill is adamant there is still plenty of room for improvement.
The Blues boss said: ‘I am not satisfied with them.
‘Just because we keep three clean sheets on the bounce doesn’t mean you can say “right, that’s it, we’re sorted, there you go now”.
‘I think there’s always improvements you can make.
‘If you played this back four together in 20 games time they will be better then than what they are now. It’s still early days.
‘This back four hasn’t even been together for the length of a pre-season.
‘Yet, because we have had three clean sheets, everybody is dancing thinking we’ve cracked it. You can’t do that.
‘They have done very well and I am really pleased with them. Really pleased. More than I will ever let on.
‘But for me there are also characters in there that if I fall over them too much they could drop into sloppy ways again. So, just in case they are reading this, there is still an improvement to be made.’
It was Aaron Mokoena’s work permit problems which initially united the current back four.
That prompted a recall for Rocha for the trip to Doncaster.
He partnered Halford in the centre of defence for the first time and Pompey have shut up shop ever since.
Cotterill added: ‘With Greg, if I was speaking to the Wolverhampton Express & Star I would say “he’s been very, very poor, Mick”.
‘For the Portsmouth News, I would say “he hasn’t done too bad”.
‘I think it has helped him being in there with Ritchie on the outside of him, who doesn’t get exposed very often.
‘Ricardo is always very good in and around our box and is starting playing better higher up the pitch than he did earlier in the season.
‘And Hermann’s experience and leadership qualities back there have helped us.
‘He is tough so people don’t get an easy time when they come up against us.
‘Jamie’s another one. He hasn’t been overworked and I’m pleased for him.
‘He has kept a few clean sheets after, for the first six months of the season, he’d been tipping over the bar, tipping them around the post, coming out and diving at people’s feet, only for us to then concede a sloppy goal.’