REPORT: West Brom 1 Wigan Athletic 0
The visitors only really showed up inside the final quarter, by which time the home side had hit the woodwork three times in total and missed a couple of sitters as well as opening the scoring through Daryl Dike.
Latics suffered their first blow before the game even started, with Jack Whatmough - named in the starting XI - not appearing along with the rest of his team-mates.
A reshuffle saw Ryan Nyambe step up from the bench, and Tom Pearce promoted to the squad.
West Brom started well and created a massive chance to go ahead, only for Jayson Molumby to stab the ball wide of the mark from six yards.
Latics managed to negotiate the opening quarter without further alarm, but fell behind on 27 minutes.
There was an element of fortune about it, as Dike headed home from a yard after the ball bounced on the Latics bar.
But Ben Amos will possibly feel he might have done better than to parry Molumby's shot into the air.
It was almost 2-0 when a free-kick from the right went all the way across the Latics six-yard box, and Dara O'Shea headed over from six yards.
Latics were seeing very little of the ball in the attacking third, with Will Keane sending their only shot in the first period well wide of the target.
Thelo Aasgaard and Joe Bennett came out for the second half, with Christ Tiehi and Nyambe the men to make way.
But West Brom continued to dominate, with Conor Townsend's 20-yard effort forcing a very good save from a diving Amos.
Jed Wallace then raced clean through down the left channel, only to smash his shot against the near post and away.
Latics made another change with Josh Magennis taking over from Keane to join Ashley Fletcher up top.
And the visitors immediately enjoyed their best spell of the whole game.
Fletcher crossed for Magennis to head just over the top, before Fletcher this time tried his luck from the edge of the box, only for Nathaniel Chalobah to make a timely block.
Aasgaard forced a fine save from Josh Griffiths, before Fletcher sent another effort just wide of the post.
West Brom almost killed the game when John Swift struck a beauty from 25 yards, only to see it come back off the Latics bar.
And the precarious nature of the lead was underlined when Magennis sent a free header straight at Griffiths
Pearce took over from McClean for the last couple of minutes plus stoppages.
And the substitute almost made himself a hero in added time, only to see his volley tipped over the bar superbly by the Baggies goalkeeper.
With Huddersfield drawing at home against Bristol City, Latics are now propping up the rest on goal difference – five points adrift of safety – with only 11 games to go now.