Watch free-to-view highlights from the Baggies' midweek trip to Lancashire.
Preston North End beat Albion 1-0 at Deepdale on Wednesday night.
Emil Riis’ seventh-minute strike was enough to earn all three Sky Bet Championship points for the Lilywhites, despite long spells of Baggies domination in Lancashire.
Steve Bruce made six changes to Albion’s XI, bringing in Alex Palmer and Martin Kelly for their league debuts alongside Taylor Gardner-Hickman, Jayson Molumby, Okay Yokuslu and Karlan Grant.
But Preston started strongly and were only denied an opener inside three minutes thanks to a fantastic Palmer save, the goalkeeper acrobatically stopping Sean Maguire’s close-range effort.
The hosts did manage to net soon after, though. A low cross from the left found Riis at the front post, and he made no mistake in poking home.
The Baggies tried to hit back, however Grady Diangana shot wide twice and Jed Wallace also fired off-target.
As half-time approached the teams exchanged blows again, Ali McCann hitting the post for Preston before Wallace and John Swift forced Freddie Woodman into good saves, yet it remained 1-0 at the break.
Albion came out full of intent and were unfortunate not to be given a penalty when Diangana looked to have been brought down inside the area.
Woodman had to be at his best once more to prevent Karlan Grant from equalising around the hour mark, the striker seeing his finish somehow pushed away, with substitute Tom Rogic testing him too.
Bruce turned to Brandon Thomas-Asante and Matt Phillips in the final 20 minutes while his side attacked almost continuously.
But Preston sat deep to grind the game out and earn the win, condemning the Baggies to a second straight Championship defeat.
Albion: Palmer; Gardner-Hickman, Kelly, O’Shea, Townsend; Molumby (Rogic 58), Yokuslu (Livermore 58), Swift (Phillips 74); Wallace, Grant (Thomas-Asante 71), Diangana.
Substitutes: Button, Pieters, Reach.