ALBION'S luckless home run continued as Deon Burton's 59th-minute winner sentenced the hosts to a harsh defeat.
And the Baggies suffered a double blow in stoppage time when substitute Neil Clement and Darren Carter both saw red.
Tony Mowbray's men dominated the game for long spells but were undone by a second-half sucker punch as in-form Wednesday stretched their unbeaten run to ten games with a fourth successive win.
The defeat continued Albion's bizarre sequence of results against teams beginning with 'S', having failed to win in ten attempts this term.
It also extended the Baggies' winless Hawthorns run to five games.
Mowbray named an unchanged starting XI while fit-again duo Kevin Phillips (illness) and Clement (ankle) replaced keeper Luke Daniels and Ronnie Wallwork on the bench.
Wednesday made two alterations as Burton and Frank Simek replaced ineligible Albion loanee Steve Watson and Leon Clarke.
Fourth-placed Albion started the game eight points and seven berths better off than Wednesday, who sat six points off the play-off places.
A lively opening to the game saw Steve MacLean and Diomansy Kamara way off target with two long-range efforts.
Carter then tried his luck from 25 yards but saw his low drive fly straight at Owls keeper Iain Turner.
Albion carved out the game's first clear-cut chance in the sixth minute when Nathan Ellington's sublime skill sent strike partner Kamara clear of the visiting defence.
However, the Senegal ace delayed his shot too long, enabling Owls centre-half Richard Wood to deflect his shot wide with a last-ditch challenge.
Albion were now beginning to build real momentum and Carter well and truly stung Turner's hands with a 20-yard piledriver which the on-loan Everton keeper gathered at the second attempt.
Just 60 seconds later, it took a great challenge by recovering Wednesday left-back Tommy Spurr to block Kamara's path to goal after the striker had been sent clear by Paul Robinson's terrific diagonal ball.
The Albion pressure continued when Zoltan Gera flashed a header wide from Carter's corner.
Kamara was proving the most dangerous player on the pitch and Robert Koren was the next team-mate to create an opening for him when the Slovenian picked out his right-wing run.
The ex-Portsmouth ace raced into the box before drilling into the side-netting from an acute angle.
Wednesday didn't record their first shot on target until the 25th minute when Burton drove straight at Dean Kiely from the edge of the box after being set up by the lively Chris Brunt's slide-rule pass.
Back came Albion and Gera sent a swerving shot into Turner's midriff after neat build-up play involving Carter and Ellington.
But Wednesday suddenly burst into life in the 27th minute.
It took a timely block in a crowded goalmouth by Sam Sodje to keep out Wood's goalbound effort from Brunt's corner.
Just a minute later, Burton and Marcus Tudgay combined to thread MacLean through.
But the Wednesday forward took the ball too wide as he rounded Kiely and could only fire into the side-netting.
Albion hit back and Ellington was denied a certain goal when Owls skipper Lee Bullen somehow deflected the ex-Wigan man's close-range shot wide from the marauding Martin Albrechtsen's low cross.
Bullen again proved Ellington's nemesis within a minute.
Turner punched Jonathan Greening's centre straight to the £3million man who thundered a shot goalwards, only to see his effort smack into the pain-stricken Bullen's privates!
Ellington's agony continued when he saw a ten-yard snapshot from Greening's corner creep inches wide of the beaten Turner's right-hand post, as an action-packed half drew to a close.
Albion pegged Wednesday back from the restart as they pummeled the Wednesday box with crosses.
And Koren wasn't too far away with a 20-yard drive which deflected off an Owls defender and screwed wide.
Carter then ruined a terrific burst from inside his own half when he nudged the ball too far in front of him as he bore down on goal, allowing Turner to gather.
But Albion found themselves a goal down against the run of play in the 59th minute.
Kiely did heroically well to get a hand to Burton's close-range prod from Brunt's pinpoint centre, but the ball just crept over the line before the Baggies keeper recovered to claw it away.
Mowbray reacted by replacing Greening with Jason Koumas.
But the Baggies boss had to make an enforced change shortly after when on-loan defender Sodje limped off and was replaced by Clement.
Kiely was called into action again in the 72nd minute when he changed direction brilliantly to keep out Brunt's deflected 30-yard drive.
Albion regrouped and went agonisingly close when Kamara sent a downward header inches wide from Albrechtsen's hanging cross after great play by Gera.
Koren went just as close in the 76th minute when he curled a 20-yard drive just past the post.
Bullen produced another goal-saving block moments later to keep out Carter's close-range effort from Koumas' pull-back.
Albion were now turning the screw and sub Phillips headed just over from Kamara's centre.
But when Koren and Kamara saw late efforts flash narrowly wide, the Baggies knew their luck was out.
And Albion's misery was complete during a dramatic spell of stoppage time.
In the 92nd minute, Clement was red-carded following a clash with Wednesday sub Clarke before Carter was also giving his marching orders two minutes later when he was shown a second yellow for a late challenge on the same player.
ALBION (4-4-2): Kiely, Albrechtsen, McShane, Sodje (Clement 68), Robinson; Gera (Phillips 76), Koren, Carter, Greening (Koumas 60); Ellington, Kamara. Subs not used: Hodgkiss, Chaplow.
SHEFFIELD WEDNESDAY (4-4-2): Turner; Simek (Hills 90), Wood, Bullen, Spurr; Tudgay, Whelan (Folly 75), Lunt, Brunt; Burton, MacLean (Clarke 80). Subs not used: Adamson (gk), Johnson.
GOALS: WEDNESDAY - Burton (59).
BOOKINGS: ALBION - Kiely (handball 65), Carter (foul 71), Robinson (kicking ball away 78). WEDNESDAY - Tudgay (foul 69), Clarke (ungentlemanly conduct 90+2).
SENDINGS-OFF: ALBION - Clement (violent conduct 90+2), Carter (second bookable offence, foul, 90+4).
REFEREE: N Swarbrick (Lancashire).
ATTENDANCE: 20,415.
ALBION STAR MAN: Zoltan Gera.
(PICS BY LAURIE RAMPLING)
