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...
9. Attacking-midfield - Gareth Evans
The fans' favourite has started the season as Kenny Jackett's preferred option. Michael Jacobs has arrived to fill the No10 role but Evans won't give up his place without a scrap. Photo: Joe Pepler
10. Left wing - Ronan Curtis
The winger will be hoping to catch the eye in front of the Sky Sports cameras against Premier League opposition. Photo: Joe Pepler
11. Striker - John Marquis
The ex-Doncaster man will be hoping for more service than he got against Shrewsbury Photo: Joe Pepler
12. Sub 1 - Duncan Turnbull
A big experience for the American keeper to be on the bench at the Amex Photo: Joe Pepler