First-half goals from Jack Colback and Fabio Borini on Wednesday continued Sunderland's "miracle" run - a phrase used by head coach Gus Poyet after Saturday's 1-0 success at Manchester United - as Sunderland avoided the drop with a fourth straight victory.
West Brom, three points clear of the relegation zone, remain within third-bottom Norwich's grasp heading into the final round of fixtures on Sunday, but a huge goal difference swing makes Pepe Mel's team effectively safe from the dreaded trapdoor.
Colback opened the scoring after 13 minutes and Borini made it two just after the half hour with his third goal in his last four games, as West Brom struggled to get going.
West Brom responded with a second-half fightback, but could not breach Sunderland's rearguard to get the point they needed for mathematical safety.
After a cautious opening, with both teams defending deeply, Sunderland - unchanged for the fifth game in a row – created the first opportunity in the seventh minute when Borini found himself in space 30 yards out, and his fierce drive was smartly turned over by Ben Foster in the Albion goal.
It was slack marking that allowed Sunderland to take the lead after 13 minutes. Full-back Marcos Alonso was able to get a cross in unhindered from the left, and Colbeck arrived in front of two hesitant Albion defenders to prod a finish that bounced over Foster for only his third goal of the season.
Sunderland continued to do most of the pressing, with Adam Johnson enjoying a lot of freedom on the right wing.
Johnson's run and whipped cross after 23 minutes caused brief panic in the Albion defence before the ball was nervously hacked clear by Diego Lugano.
But the hosts doubled their lead just after the half hour with a beautifully crafted goal. Sebastian Larsson spotted the run of Borini and found him with a lovely chipped pass that the on-loan Liverpool forward steered neatly beyond the advancing Foster.
The first half ended with Albion creating their first serious opportunity, when a good run by Saido Berahino and curling shot from the edge of the box was pushed away by Vito Mannone at full stretch.
West Brom looked the more lively side after Mel's half-time team talk and Victor Anichebe came within inches of getting on the end of substitute Craig Dawson's low right-wing cross at the back post after 56 minutes.
Two minutes later, Stephane Sessegnon – given a good reception by the home fans on his return to Sunderland - struck a shot narrowly wide from 30 yards as the visitors continued to respond well.
Sessegnon was again the danger man just past the hour mark when his weaving run beat two defenders, but he screwed his left-footed shot wide from 15 yards.
Jozy Altidore, only just on the pitch as a second-half substitute, should have put the game beyond doubt when he stretched to send a shot wide from eight yards with the goal at his mercy, after Colback had found him with a left-wing cross.
A good sweeping move set up Santiago Vergini with 21 minutes remaining on the right-hand side of the box, but his drilled finish went inches wide of the left-hand post.
With both teams trading attacks, the game reached a stalemate as West Brom slipped to back-to-back defeats, while Sunderland celebrated beating the drop.
