Diomansy Kamara's well-taken winner handed West Brom a crucial away win in a pulsating Coca-Cola Championship play-off semi-final first leg at Molineux.
Both sides held the lead in a game that ebbed and flowed but was frequently dominated by the home team, but Tony Mowbray's clinical Baggies will now be confident ahead of Wednesday's return at the Hawthorns.
Kevin Phillips had given Albion the lead in the 25th minute when he rifled home from 20 yards after Gary Breen mis-kicked his clearance straight to the former Sunderland striker.
But centre-half Jody Craddock, another ex-Black Cat, rose to brilliantly glance Andy Keogh's left-wing cross into the far corner in the 44th minute to give Wolves a half-time boost.
Seyi Olofinjana collected Neill Collins' head-down to fire home from close range five minutes after the restart, but a minute later Phillips was on hand again to head in a corner at the far post and level the scores.
And the Baggies were bouncing again in the 72nd minute when Breen was once more at fault - playing Diomansy Kamara on-side and allowing the striker to home in on goal and place a shot past debut-making keeper Wayne Hennessey from an angle.
Manager Mick McCarthy suffered a devastating blow ahead of the clash - billed locally as the biggest Black Country derby ever - when highly-rated goalkeeper Matt Murray was ruled out with a suspected broken shoulder.
Untried youngster Hennessey, shipped out on loan earlier this season, was brought in for his Wolves debut as the only change from the side that beat Leicester last time out.
West Brom recalled 20-goal striker Kamara after suspension, with Nathan Ellington dropped to the bench.
Wolves started well and Keogh had already headed meekly at Dean Kiely before he played in Michael Kightly, whose attempted chip over the sprawling keeper was palmed away. The home side came even closer in the 12th minute when Michael McIndoe's corner was headed goalwards by Olofinjana, but Robert Koren was on hand to nod the ball off the line.
Minutes later, Breen saw his header from McIndoe's right-wing free-kick flash narrowly wide of the post.
Albion's first sighter soon followed, but Phillips' weak shot could not live up to the fine driving run which preceded it.
But against the run of play it was the visitors who opened the scoring when Phillips finished brilliantly from the edge of the area.
Just after the half-hour Wolves had a chance to level when Olofinjana played in Kightly, but again the on-rushing Kiely palmed away his effort.
The lively McIndoe turned creator again the 38th minute but his back-post cross was headed over by Bothroyd.
And the home crowd were then in raptures as Craddock headed them back into the game just before the break.
Kamara had the first chance of the second period when his jinking run created room in the box, only for the striker to slice wide from eight yards.
Five minutes in Wolves took the lead for the first time through Olofinjana's tap-in, but Phillips wasted little time in getting West Brom back on terms.
The Baggies brought on Zoltan Gera for Koren in the 62nd minute in an attempt to push for a winner, and Phillips was almost in soon afterwards but stopped for an offside flag that never came.
It turned out to be his last contribution before he was removed for Ellington, perhaps with Wednesday night's return in mind.
And Mowbray's decision was vindicated with 18 minutes left when Kamara finished coolly from 10 yards.
Kamara fired wide again soon afterwards and Sam Sodje headed past the post as West Brom finished the stronger on an increasingly sodden pitch.
Bothroyd went close and Kightly forced Kiely into a low save with a 20-yard drive in injury-time but the visitors held on for a famous win.
