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...
17. Sub 6 - Michael Jacobs
The new-boy is short of match fitness but looks set to be involved on the bench. Photo: Lewis Storey
18. Sub 7 - Ellis Harrison
The striker continues to push for a starting spot after recovering from a calf injury in pre-season Photo: Joe Pepler
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