David Norris has sensed there’s something very different about what he is going to encounter on Sunday.
The Pompey midfielder has played in derbies but has detected an intensity to the rivalry between his side’s supporters and that of their friends from along the M27 he has not previously come across.
A long line of prominent and respected football figures who have tasted derbies the world over will tell him he’s right to have that feeling.
Norris felt hatred was a strong word to use when describing the emotions between two sets of football fans.
In the case of Pompey and Southampton it is the right one, Chuck.
This isn’t sensationalism or a rose-tinted assessment of the ferocity which fuels the south coast showdown.
Harry Redknapp is as well-placed as anyone to assess the rivalry between the clubs.
‘It’s a strange hatred,’ said the man branded Judas for crossing the divide in 2004.
‘I haven’t known another like it.’
Having personally witnessed supporters turn their back on Redknapp as he attempted to shake hands with them after his return to the club, I can see how he has arrived at that verdict.
So why does that antagonism exist between the two clubs? And what fuels it?
The fact there is a historical rivalry between the cities and their maritime existence is an obvious starting point.
Anger over dockers from Portsmouth crewing the Titanic’s sister ship in 1912, and the accusation the South Coast Union Men (SCUM) of Southampton crossed the picket line when Portsmouth dockers went on strike in the 1950s led to ill-feeling on both sides. Pompey have their proud naval heritage, while Southampton’s port has a largely commercial history.
The geography could be another factor, too.
The fact the cities are 20 miles apart means they have always been close enough to be aware of each other but far enough away to give the rivalry a tribal element.
In homes across Merseyside, supporters exist in the same household.
A similar scenario is a rarity in these parts.
Then there is the varying fortunes of the two clubs down the years, with one outfit’s star often on the rise as the other is in decline.
That has often meant meetings have been fleeting, allowing resentment to fester at the other team’s superior status.
Maybe, though, it’s just the fact the two communities simply breed a different type of character.
Portsmouth’s island mentality and naval links perhaps lends itself to an emphasis on different traits to its more modern, perhaps fashionable neighbour.
Whatever makes it what it is, when the cities’ two football clubs come together it makes for a special occasion.
That will be the case on Sunday as Fratton Park becomes a heaving hothouse when hostilities recommence.
There is little doubt the balance of power is shifting back along the M27, with Southampton flying high in the Championship.
That follows a period where the men from PO4 have undoubtedly been in the ascendancy.
Despite FA Cup glory, it’s two 4-1 victories over Southampton which rate highest in the recent glory days for many followers of the star and crescent.
Ask Pompey fans whether they would accept a couple of victories this season over ‘that lot from down the road’ at the cost of them gaining promotion, and the vast majority would bite your hand of for it.
That in itself is a revealing insight into a rivalry that stands on its own.