John Sheridan blamed his Newport County players for their naivety as they went down by a single goal to Pompey.
League Two’s bottom club have managed just one win in their opening 13 games and are already three points adrift of safety.
While they were certainly competitive, they failed to create many opportunities, although they did have a first-half goal by Lenell John-Lewis harshly chalked off for a supposed push on Christian Burgess.
Sheridan refused to use that decision as an excuse for his team’s failings and instead pointed to the crucial moments before half-time when Kyle Bennett found Matt Tubbs in the box to fire home the winner.
The Newport boss said: ‘I don’t know what our goal was disallowed for, the ref said there was a push, but we cannot make excuses, we have to turn it around.
‘The goal is an example of how naïve we have been.
‘It is just before half-time and it is typical of a team who are bottom of the league.
‘It was criminal, people are making random decisions and it costs us. We need to do better.’
The former Sheffield Wednesday midfielder has only recently joined the Welsh outfit after Terry Butcher was sacked.
And the former Republic of Ireland international pointed to Pompey’s attention to detail as a key difference.
He said: ‘They had the players who didn’t ignore the simple things, which makes good players. But our work-rate was really good.
‘I am trying to help the players but I have to be honest and we are bottom of the league for a reason, we are losing football games.
‘They just had people keeping the ball and we were naïve in our decision-making. It meant we gave the ball away cheaply.
‘There was nothing between the sides in the first half, I was happy with the way things were going.
‘But we left ourselves vulnerable at times.’