The Blues will be aiming to pull off an upset against the Premier League hosts at the Amex Stadium.
Kenny Jackett has to weigh up the starting line-up against the Seagulls, with a League One trip to Rochdale on Sunday to also plan for.
The boss has said he wants some continuity, though, as he looks for Pompey to get into a winning rhythm.
Here's how we think the Blues could start...
1. Goalkeeper - Craig MacGillivray
Will be relishing regular action once more and had a fine game against Shrewsbury on Saturday. A chance to impress the Scotland selectors with the game on Sky Sports. Photo: Joe Pepler
2. Right-back - James Bolton
With Callum Johnson cup-tied, Bolton will be eager to impress on his recall to the team. Photo: Jason Brown
3. Right centre-back - Jack Whatmough
There are some doubts whether Gosport lad can handle three games in eight days, but he says his body is feeling good. Been imperious since his return to the team. Photo: Joe Pepler
4. Left centre-back - Sean Raggett
A mainstay in Pompey's defence these days and formed a decent partnership with Jack Whatmough. Photo: Joe Pepler