Leicester need to beat Albion on Saturday to be certain of going up.
Third placed Sheffield United put the promotion celebrations on hold for Micky Adams' side by beating Nottingham Forest 1-0 at Bramall Lane last night with a Carl Asaba goal.
Leicester require a maximum of two points from their remaining four matches.
Portsmouth clinched promotion and returned to top spot, two points clear of Leicester, with a 1-0 win against Burnley at Fratton Park.
Svetoslav Todorov's 20th goal of the season in the second half sent Pompey back into the top flight for the first time in 15 years.
Boss Harry Redknapp said: "I'm stunned by what has happened and you can see just what it means to the people of Portsmouth by their reactions at the final whistle."
Walsall and Coventry eased their lingering relegation fears with a 0-0 draw at the Bescot Stadium.
Walsall are seven points clear of Albion and Coventry nine.
Reading remain on course for the play-offs after thrashing nine-man Preston 5-1 at the Madejski Stadium, including a hat-trick for Nicky Forster.
Michael Jackson, who opened the scoring for Preston at Withdean last Saturday, and keeper David Lucas were sent off.
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