Lee Bradbury is urging the Hawks to show their real quality in front of the home fans as Hemel Hempstead Town visit Westleigh Park on Saturday (3pm).
It is something they have failed to do consistently so far this season in National League South.
Away from home the Hawks have been impressive, losing only once on their travels.
These performances on the road are the main reason why the Hawks have climbed up to fifth in the league.
At home, however, they have not got such a good record.
Bradbury’s side have won just twice in the league in front of their own fans.
The manager accepts this is not good enough and needs to change if his side are to maintain a realistic push for the play-offs.
There is a lot riding on the game with the Hertfordshire visitors one point and one place above the Hawks.
The Hawks are hoping for a bumper crowd and Portsmouth fans not travelling to Blackpool can take advantage of the £5 entry offer for season ticket holders at Fratton Park.
‘This is a big game for us and it makes a huge difference to the players if they have got a good crowd behind them,’ said boss Bradbury.
‘Our home form hasn’t been the best this season but we are looking to change that.
‘A lot of teams have come to Westleigh Park and parked the bus.’
‘Our performances have not been bad but we must be better in both boxes.
‘The only home game where I felt we have been second best was against Bath City.
‘We must not give away silly goals and have to take our chances when they come along.
‘I am backing the team to show the same intensity and desire they have produced away from home.’
The Hawks have created more chances than their opponents in most games this season.
It is a question of converting more of those chances, particularly at home.
Striker Jason Prior has scored in each of his last eight league games.
Bradbury insists other players have to contribute more in the goalscoring stakes.
‘We need other players to start chipping in with more goals,’ said the Hawks manager.
‘When the chances come along we have to be ruthless.
‘We have shown it away from home, now we need the same at home.
‘Hemel Hempstead are also in the top six so it won’t be easy.
‘It will be interesting to see if they are prepared to come and have a go at us.’
Bradbury has a full squad to choose from apart from Brian Stock who is recovering from knee surgery.
Hawks: Young, Williams, Woodford, Harris, Strugnell, Lewis, Fogden, Carter, Tarbuck, Robinson, Prior, Rose, Molyneaux, Widdrington, Rutherford, Hayter, Tubbs