Wigan are clinging to their Barclays Premier League status by the thinnest of threads after two calamitous defensive errors condemned them to a 3-2 defeat against Swansea.
Twice ahead through Roger Espinoza and James McCarthy, the Latics were floored by second-half goals from Angel Rangel, Itay Shechter and Dwight Tiendalli.
Defeat leaves Wigan three points adrift of safety with two matches left.
Their next assignment is Saturday's FA Cup final against Manchester City before they face a daunting trip to Arsenal next Tuesday, by which point their fate could be all but sealed depending on the results of their relegation rivals this weekend.
Edin Dzeko struck against West Brom for the third time this season as Manchester City edged a 1-0 victory at the Etihad Stadium.
The Bosnian, whose double at The Hawthorns in October included a last-gasp winner, guided home a volley after 35 minutes of a Barclays Premier League clash lacking in intensity but not incident.
Both sides spurned numerous chances with City hitting the woodwork twice through Carlos Tevez and James Milner in the first half and Marcus Rosenborg doing likewise for West Brom after the break.