Jamie Ashdown warned his Pompey team-mates they have to cut out their defensive doziness.
The Blues had to again come from behind to pick up a share of the spoils in yesterday's 1-1 Boxing Day clash with Millwall.
David Nugent's second-half strike cancelled out Liam Trotter's opener for the Londoners.
That means Pompey have now fallen behind in five of their last seven league outings.
Ashdown, who was again excellent for his side against the Lions, knows gifting leads to sides like that cannot continue.
The 30-year-old made a series of decent stops.
But Ashdown feels that counts for little if his team can't start showing greater defensive steel.
He said: 'We really want to be winning our home games.
'It's disappointing but we haven't lost.
'Their goal was against the run of play but their guy got up well to take the second chance from the header.
'We should have been a bit more switched on, though.
'We are scoring in every game but we don't want to be clawing it back all the time.
'That was what happened at Swansea but we sorted it at Norwich. We improved and addressed that but we haven't against Millwall.
'We keep conceding these early goals.'
Ashdown, above, has targeted an improved second half of the campaign for his side, especially on the back foot, if they are to challenge for the play-offs.
He said: 'Of course we want to get up the table as quickly as we can.
We're getting there but it's bits and bobs at the moment which are costing us – and that has to stop.'