A one-sided first half saw the Baggies take control of the clash and forced Wednesday to settle for a storm-weathering session with only Djeidi Gassama offering a great deal in terms of an outlet. The second half turned along with a system switch-up and Owls substitutes made a difference - with chances falling to the away side as the game went on.
A classy Adam Armstrong finish seemed to set up a home win before subs Svante Ingelsson and Callum Paterson combined to grab what could have been a dramatic equaliser - before Jason Molumby diverted a last-gasp corner home to take the three points.
Here are our ratings from another topsy-turvy afternoon with Sheffield Wednesday.
9. Josh Windass - 6
Strapped on the captain's armband in Bannan's absence. Involved in some of their few attacking bits and pieces on the day and dared to carry the ball. But nothing really turned as with everyone else. Yellow'd for grabbing the ball on the deck. | UGC
10. Michael Smith - 6
Got about and pulled defenders round. Provided muscle. Didn't get much in the way of chances. Cut a frustrated figure for big periods but never stopped putting it in. Off with five left. | UGC
11. Djeidi Gassama - 7
Wednesday's outlet-in-chief and a cause for intrigue more or less every time he got the ball. Guilty of trying too much once or twice but you encourage that for a player in that form. Disallowed goal stung a touch. | UGC
12. Marvin Johnson - 8
Back on the pitch in place of the injured Bernard. Raced across to produce a vital block to deny Diangana. Put in one cross in particular that deserved more and did well to wrap his foot round a shot that went just wide. Released Ingelsson for the Owls goal. | UGC