Paul Cook admits he is wary of inflicting too many formation switches on his Pompey team.
The Blues’ players have been schooled in the ways of 4-2-3-1 since the manager arrived at the club in May.
I am not suggesting we can’t but it’s not like a flick of a light where you think you canPaul Cook
It has been the primary system which has carried Pompey into second place in League Two and undefeated after eight league games.
Although a plan B of 3-5-2 paid instant dividends in the second half against Barnet, Cook favours his tried and tested method.
It is for good reason, too, having won promotion from the bottom division at Chesterfield in 2014-15.
Pompey head to Bristol Rovers on Saturday seeking to extend their bright start to the campaign.
And once again the 4-2-3-1 remains at the forefront of his preparation.
Cook said: ‘At Chesterfield we used to go 4-4-2 as an alternative system and were rubbish at it!
‘We were horrendous. We got beat 4-3 at Morecambe, 3-2 at Newport, you don’t release that you build these lads to play in a way and then in a space of a blink are expecting them to go completely against that.
‘For me, 4-4-2 is about hitting your front two early, support and crosses into the box.
‘We are building a team to play possession football and then all of a sudden because the game is not going well let’s all change – and we expect the players to be able to do it.
‘I am not suggesting we can’t but it’s not like a flick of a light where you think you can.
‘I believe all successful teams have a way of playing irrespective of whether that is 4-4-2.
‘Our problem at the moment is every team has changed how they play to play against us so that is something we can overcome.’