Albion, Reading and outsiders Blackburn will battle it out for one remaining play-off spot on the final day of the Championship season.
Wigan booked their place in the semi-finals with a 1-0 win at Birmingham City last night.
Callum McManaman scored early to heap more home misery on Birmingham, who remain in the bottom three.
Albion will reach the play-offs if they win at Nottingham Forest on Saturday and Reading drop points at home to Burnley.
The Seagulls would almost certainly make it with a draw should Reading lose.
Blackburn are not quite out of it but host Wigan needing to make up three points and seven goals on their rivals.
Meanwhile Charlton are safe after a 3-1 win at home to Watford tonight.
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