Leeds are moving visiting supporters out of Elland Road’s South Stand and into the West Stand tomorrow in a bid to crank up the atmosphere.
Pompey fans will be the first set of supporters not to sit behind one of the goals at the ground.
Leeds have spent £300,000 redesigning the West Stand to create segregation between home and away supporters.
The change will mean home fans can take up seats behind both goals at Elland Road for the remainder of the Championship season.
Pompey’s allocation of 1,100 tickets and all future allocations will be situated to one side of the pitch.
It means they will be charged the West Stand price of £36 for adults and £25 for children.
Manager Simon Grayson believes the move will be a ‘big advantage’ to his side.
And Leeds chief executive Shaun Harvey has backed the decision.
Harvey said: ‘The changes are taking place tomorrow and Portsmouth’s supporters will be in the West Stand.
‘These are always the last seats to be sold even when sell-outs occur and it’ll allow us to police and manage visiting supporters more economically.
‘But the manager and the players also felt it would be a big advantage to have our own supporters behind both goals.
‘That was a major consideration.’
Meanwhile, midfielder Adam Clayton believes Leeds are on the verge of mounting a serious assault on the Championship.
The Yorkshire club are currently in 13th spot, two points ahead of the Blues, and drew 3-3 at Brighton in their last fixture.
But the youngster believes things are coming together and that Leeds can kick-start a push against Steve Cotterill’s men tomorrow.
Clayton said: ‘I don’t think anyone is tearing us apart and we’re not fearing anyone.
‘It has been more a case of individual mistakes in games.
‘Brighton are a good team and for long periods we coped with them well.
‘But it was one of those games we should have won, like a few this year.
‘We have to look to stop it and come out with three points in games like that.
‘There have been a few dodgy sendings off as well in games which shouldn’t have happened and that means the manager has had to change things around.
‘But it’s a great group of lads here and everyone is in it together.
‘When we go behind, we never stop and we try to get back in the game. And we’ve done that.’