The game dubbed ' El Creekio' - as both clubs are situated on Fareham Creek - is expected to be an exciting affair.
Both teams are in excellent form and like to play attacking football.
The Royals are the second highest scorers in the league with 32 goals from ten games.
And Fareham warmed up for the game with a startling 7-1 demolition of league leaders Alresford Town - taking their goal tally to 14 in three matches.
Both managers Mick Catlin and Pete Stiles believe there won't be a lot between the two sides.
'This is a big game for both teams,' said Royals boss Catlin.
'It is all set up to be a cracking game because both teams will go all out for it.
'We won't be approaching it any differently just because it is a local derby.
‘Our aim is to go out and try to win every game.
'I don't think either of the two teams are capable of sitting back and soaking up pressure.
'Both games were drawn last season and they are always close affairs.'
The home side possess a potent strikeforce with the likes of Dan Wooden, Jason Parish, Nathan Paxton and Mike Turvey.
Wooden grabbed a brace in the 3-2 win against Fleet Town with Paxton also notching a goal.
Second-placed Portchester are unbeaten in their last nine games.
The Reds are 13th and have been playing catch up after a stuttering start.
They showed against Alresford, however, that they are increasingly becoming a force to be reckoned with.
Stiles - who used to manage Portchester’s reserves - is adamant his team won’t be sitting back tonight.
'If you don't have a go then you will never know,' he declared.
'We can't afford to sit back and play for a point.
'That is not our style anyway.
'I do think this will be a tougher game than the one against the leaders.
'It is bound to be a competitive, hard-fought affair, but thrashing Alresford has given us a huge confidence boost. The players now know that they can do that.
'On our day we are capable of beating anyone in our league.
'This is the first of three games between the teams in a month.
'By the end of it we will be sick of the sight of each other.'
The home side will need to keep the shackles on the Reds front pair of Luke Slade and Josh Benfield.
Slade scored four times against Alresford and Benfield has struck seven times in five games since arriving from Paulsgrove.