A win for Fulham or even a draw at The Stadium of Light will pull the leaver that opens the relegation trap door.
A win for Pompey, WBA or Birmingham will relegate Sunderland anyway, whatever happens against Fulham.
As for Fulham a win is needed to help keep their Premiership status intact. The drop zone is just 9 points below and Fulham have played a game more than most, two games more than Pompey.