Thomas Gaardsoe's dramatic injury time winner pushed West Brom closer to an instant return to the Premiership.
Danish central defender Gaardsoe capped a frantic final 17 minutes as ten-man Wigan's own automatic promotion hopes suffered a major setback, Wigan, who are now a massive 12 points behind second-placed Albion, looked to be on course for their first ever win at The Hawthorns when Andy Liddell fired them ahead from the penalty spot in the 73rd minute.
But Lee Hughes equalised with a spot-kick two minutes later with Wigan also being reduced to ten men in the process by the dismissal of goalkeeper John Filan.
Hughes then had a hand in Albion's winner when he set up Gaardsoe.
The win keeps second placed Albion level on points with leaders Norwich City who have a game in hand.
Wigan had shown their determination to try and pick up a vital victory when Jason Jarrett and Neil Roberts were booked for crunching tackles inside the opening 19 minutes.
Albion struggled to cope with Wigan's high-tempo fast start and it needed a long-range drive from Hughes in the 17th minute, that was well held by Filan, to calm their nerves.
But Wigan also carried their own threat in attack and leading scorer Nathan Ellington was inches away from firing them ahead when his headed a cross from Liddell just over the bar after 23 minutes.
It was a warning that Albion heeded and Hughes should really have broken the deadlock 60 seconds later when he failed to convert a centre from Geoff Horsfield in front of an open goal.
Hughes also volleyed just wide in the 38th minute as Albion enjoyed a sustained spell of pressure.
But the more clear cut chances were being created by Wigan and it needed a last-ditch block from Gaardsoe to prevent them opening the scoring in first-half stoppage time.
Gaardsoe was in the right place at the right time to block a fierce goalbound drive from Roberts.