Wigan needs just a point from its final match to ensure it finishes fifth and meets QPR in a playoff.
Wigan Athletic sealed its place in the Championship playoffs with a 1-0 win at relegation-threatened Birmingham City on Tuesday.
Callum McManaman scored after just three minutes at St. Andrew's to move Uwe Rosler's side four points clear of seventh-place Brighton and Hove Albion with just one game remaining.
Wigan requires just a point from its final match of the season — which comes at Blackburn Rovers on Saturday — to ensure it finishes fifth, which would lead to a playoff clash with QPR.
On the other hand, a fifth-straight Championship defeat for 22nd-place Birmingham means it needs a positive outcome at Bolton Wanderers and for other results to go its way this weekend if it is to avoid the drop to League One.
In Tuesday's other Championship fixture, Charlton Athletic secured survival with a 3-1 home win over midtable Watford.
In League One, Carlisle United missed the chance to boost its hopes of avoiding relegation with a 0-0 draw at Crawley Town.
The stalemate means Carlisle is three points adrift of safety, and it needs an unlikely win at champion Wolves on the final day to stand any hope of staying up.
Elsewhere, Chris Porter's late equalizer earned Sheffield United a 1-1 draw at Oldham Athletic.