SUPER-SUB Kevin Phillips boosted Albion's automatic promotion hopes with a last-gasp winner against the ten-man Owls.
The 34-year-old striker's back-post header from James Morrison's looping cross in the 94th minute was well deserved as the Baggies got their away form back on track
Robert Koren went close with good efforts in either half while Paul Robinson missed the chance of the game in the 38th minute and substitute James Morrison could have nicked one at the death.
But, as well as riding their luck a touch, lowly Wednesday produced some heroic defending worthy of the seventh-best defensive record in the league.
Although the hosts played out the last 12 minutes with ten men after Jermaine Johnson's sending-off, they might even have won it through Marcus Tudgay in the 88th minute.
But Phillips, who was crowned the best player in the Football League two days ago, had the last say.
Ishmael Miller dropped to the bench and Luke Moore was handed his full Albion debut alongside in-form Roman Bednar in attack.
Gera replaced the injured Filipe Teixeira (knee) at right midfield, while Phillips and Morrison returned from knee injuries to take their places on the Baggies bench.
Tommy Spurr almost got the hosts off to flier in the second minute as he cut inside from the left and drilled in a low 20-yard shot that Dean Kiely just managed to gather at the second attempt.
Two minutes later, Moore looked like sneaking in behind Richard Wood from Jonathan Greening's long diagonal ball but Lee Grant raced off his line to collect.
Adam Bolder picked out Richard Hinds with a cross from the right in the seventh minute but the Owls right-back headed straight at Kiely from ten yards.
Leon Barnett rose well at the near post from Greening's left-wing corner in the 13th minute but his header lacked the power to beat Grant.
Chris Brunt, back on his former stomping ground for the first time, surprised Grant with a shot from a tight angle two minutes later and the Wednesday keeper was lucky to have the chance to gather the ball at the second attempt as it rolled free.
The 24th minute saw Albion come closest to scoring so far as Gera retrieved an over-hit Brunt cross on the right and fired the ball to the edge of the box, where Koren's first-time volley was saved superbly by Grant.
Brunt pounced on the rebound but saw his fiercely-struck volley fly well wide of the right-hand post.
Robinson was gifted a golden opportunity to open the scoring seven minutes before the break when Enoch Showunmi headed Brunt's back-post corner straight to him.
The Baggies left-back had the whole goal to aim for but scuffed his 12-yard shot wide of the right-hand post.
Just a minute later, Johnson drilled the ball low into the Albion penalty area and Barnett had to be alert to block Tudgay's first-time strike and ensure the game was goalless at half-time.
Wednesday started the second period brightly and Tudgay was given time to tee up Graham Kavanagh, who despatched a right-footed drive just wide of the right-hand post from the edge of the box.
Gera burst past Bolder down the right in the 50th minute and got to the by-line before delivering a cross that Mark Beevers cut out ahead of Moore in the six-yard box.
Brunt set Moore free down the left three minutes later and he cut inside Owls skipper Wood but declined the chance to shoot and tried to beat Beevers, only to be dispossessed by the young centre-half.
Brunt raced onto the loose ball and fizzed it across the six-yard box, just evading Bednar, who was jostled to the ground by Wood.
The hosts counter-attacked in the 56th minute and Kiely needed to save at the feet of Showunmi, who found room to get a shot in from 12 yards.
Bednar succumbed to an ankle injury in the 62nd minute and was replaced by Miller.
Brunt tried his luck with a 35-yard shot in the 70th minute and the ball bounced off Moore's shins to the edge of the box for Koren, who shaved the top of the crossbar with his side-foot effort.
Mowbray made another change in the 75th minute as Moore was replaced by top scorer Phillips.
The Owls were reduced to ten men three minutes later when Johnson was sent-off for an alleged elbow on Greening.
The Baggies skipper reacted to the challenge and was also booked by referee Andy D'Urso.
Tudgay looked set to pinch a shock win for Wednesday in the 88th minute but Barnett somehow did enough to prevent him getting enough purchase on his close-range volley to beat Kiely.
A minute later, substitute Morrison should have headed home Robinson's cross but only found the keeper.
However, that just left the stage free for Phillips to steal the show with his crucial 18th goal of the season of the season from Morrison's centre in the fourth minute of stoppage time.
SHEFFIELD WEDNESDAY (4-4-2): Grant; Hinds, Beevers, Wood, Spurr; Johnson, Kavanagh, Bolder, O'Brien (Sahar 68); Tudgay, Showunmi. Subs not used: Burch (gk). Burton, McAllister, Wallwork.
ALBION (4-4-2): Kiely; Hoefkens, Barnett, Albrechtsen, Robinson; Gera, Koren, Greening, Brunt (Morrison 80); Moore (Phillips 75), Bednar (Miller 62). Subs not used: Danek (gk), Martis.
GOALS: ALBION - Phillips (90+4).
BOOKINGS: SHEFFIELD WEDNESDAY - Wood (foul 65), Bolder (unsporting behaviour 90). ALBION - Greening (unsporting behaviour 78), Miller (dissent 80).
SENDING-OFF: SHEFFIELD WEDNESDAY - Johnson (violent conduct 78).
REFEREE: A D'Urso (Essex).
ATTENDANCE: 18,805.
ALBION STARMAN: Leon Barnett.
PIC: HEADS YOU WIN...Phillips nods home his dramatic winner
