Dutch full-back Zuiverloon cruised down the right before spanking a 20-yard shot which Chris Kirkland could only palm into the path of Fortune who successfully gambled with a run to far post.
Whether that stinging effort from Zuiverloon injured Kirkland is uncertain, but the former Liverpool keeper had to be replaced by Ghana international Richard Kingson after the restart.
Mid-table settlers Wigan certainly did not look like a team content to see out their last four fixtures.
Soon after the goal, the Latics streamed forward and forced Kiely into a great double save from Paul Scharner and then Olivier Kapo from a yard out.
Mowbray wants last day Baggies drama
However, luck was out for the former Charlton keeper moments later when Rodallega's low free-kick from 25 yards deflected off Brunt and spun home, though Kiely perhaps could have done better.
Juan Carlos Menseguez then should have capped his first league start for the Baggies with a goal, but his shot, after a great run, was tipped over by the busy Kingson, who then blocked an effort from Brunt.
If Kingson thought his first 36 minutes between the sticks were busy, his work-rate was to set to increase markedly after the break.
It was Wigan who had the early chances in the second half.
Effervescent winger Luis Antonio Valencia, who has been linked with a move away from Wigan, forced Kiely into blocking low down.
The keeper surpassed that effort with a superb reaction save with his foot from defender Mario Melchiot.
Play switched to the Wigan penalty area, with Jonathan Greening forcing Kingson into tipping over his shot following a powerful run down the centre.
Bruce frustrated by end of season form
Unfortunately for the valiant stand-in keeper, his defensive team-mate Bramble then clipped the marauding Fortune in the area to concede a penalty.
Brunt, the Baggies' leading scorer in the league, stepped up to the plate to fire in his eighth goal but only after Kingson had saved his initial effort with his legs.
With their tails up, West Brom hit the accelerator and scored again.
This time, Frenchman Fortune led the celebrations when he was found by Borja Valero's ball from the right before firing in a powerful drive from just inside the area.
West Brom remain bottom on 31 points but only on goal difference.
And with fourth-from-bottom Hull stuck on 34 points after a defeat by Stoke and two of bottom three, Newcastle and Middlesbrough, playing each other on Monday, the Baggies have a chance to of performing the great escape.
West Brom boss Tony Mowbray: "We're not getting carried away.
"We just keep going. I'm delighted for the supporters. We want to keep on winning and stay in the division.
"There's a nice easy one against Liverpool next week. It all rests on that game. If we can take it to the last game against Blackburn then good."
Wigan boss Steve Bruce: "I was delighted with our performance in first half, but we have to take our chances when we get them.
Bruce added: "Unfortunately, it looks like we've been in limbo for weeks. It has been very, very difficult to lift the players.
"We got to the magical 41 points with eight games to go."
West Brom: Kiely, Zuiverloon, Martis, Olsson, Cech (Donk 74), Brunt, Dorrans (Mulumbu 55), Greening, Borja Valero, Menseguez (Simpson 87), Fortune. Subs Not Used: Allsopp, Bednar, Kim, Filipe Teixeira.
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