Second-half turnaround leaves the Baggies in the top-half but stuns Steve Bruce's side, who have lost seven of last eight and are slowly being dragged into a relegation dog-fight
Sunderland, who have now lost seven of their last eight, are perilously close to the drop-zone, but this result leaves West Brom in 10th place, seven points clear of 18th place.
The hosts made four changes after their 5-0 hammering at Manchester City, with Kieran Richardson, Ahmed Elmohamady, Steed Malbranque and Nedum Onuoha replacing Jordan Henderson, Sulley Muntari, Stephane Sessegnon and Anton Ferdinand, whilst the visitors were unchanged for their win over Liverpool.
Sunderland had not scored in 440 minutes before the match, but were handed an early lead by some poor West Brom defending.
Asamoah Gyan on the left had his cross deflected and under pressure from Elmohamady six yards out, Nicky Shorey headed into his own net.
Before West Brom had a chance to kick-off, Anton Ferdinand came on for the injured John Mensah, but the home side started to dominate the match, buoyed by their fortuitous lead.
A cross from the right by Elmohamady, who was having an influential game on his return to the side, was controlled by Gyan 12 yards out who turned and shot into the side netting, with half the ground thinking it had gone in.
Kieran Richardson was then booked by referee Peter Walton for sarcastically moving the ball behind the touchline after being told to take a free-kick from further back
Captain Lee Cattermole began to protest furiously with the referee and comically knocked the yellow card out of his hand, but was fortunate that when Walton picked it up he did not brandish it at the Sunderland player.
As with the Sunderland goal, West Brom’s leveler came against the run of play and Steve Bruce will have been extremely unimpressed with his side’s defending.
A cross from the left by Jerome Thomas was deflected high up into the air, but Jonas Olsson was unchallenged as he flicked it with the back of his head from just inside the area.
Peter Odemwingie, who scored his first goal for the club in the home victory against Sunderland at the start of the season, was the first to react and he stabbed it in from a few yards out for his 11th of the season.
However, Sunderland responded well and regained the lead just two minutes later in some style.
Gyan was fouled 30 yards out and after being teed up by Kieron Richardson, Phil Bardsley slammed it into the top-left corner of the net courtesy of a slight deflection for his third goal of the season to give the Black Cats the half-time lead
Kieran Richardson, who had taken a knock in the first-half, was replaced at half-time by Bolo Zenden.
After efforts by the now booked Lee Cattermole and Chris Brunt, the West Brom equalizer came from Youssouf Mulumbu, who exchanged passes with Odemwingie before poking the ball in.
And the Baggies nearly took the lead soon after.
Brunt showed why he had the second highest number of assists this season as his brilliant free kick from the right gave Olsson a free header from a few yards out, but Mignolet pulled off a stunning save to his left
But the visitors did not have to wait long for their third goal.
After some lovely interplay, Simon Cox slipped it down the right-hand side for Odemwingie, who crossed it into the box where Paul Scharner hit it first time into the near corner of the net to start wild celebrations by both players and supporters.
West Brom began to stroke the ball around well, with Cox and Odemwingie coming close, before the former almost scored a second own goal from a Sunderland free kick, which he headed just wide.
Sunderland did not look like equalizing, but had one last chance when the quiet Danny Welbeck ran on to a Gyan flick-on, but from the left-hand side of the penalty area he blasted over.
This result leaves the hosts in 13th, but they will need to defend better if they are to avoid being sucked into the fight against relegation.
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