Former Blues boss Steve Cotterill lies in waits with five games of the League One season remaining.
His side had won their five past home games on the spin, before defeat to Peterborough last time out.
So a tough test lies in wait for John Mousinho’s side, with play-off hopes receding going into the game.
Pompey have fitness and suspension issues to consider going into the game – so this is how we think they will line up at New Meadow.
1. GK Matt Macey
Eight clean sheets and counting for the keeper who is a wanted man next season. Photo: Jason Brown
2. RB Joe Rafferty
Nailed on to continue at right-back, especially with Zak Swanson being sidelined. Photo: Jason Brown
3. CB Sean Raggett
Form has been impressive and has shown some surprising attacking flair of late, too. Photo: Jason Brown
4. CB - Clark Robertson
One of the few to emerge with credit against Morecambe on Monday, but will be pushed by Towler and Bernard. Photo: Jason Brown