Albion secured their safe passage to the FA Cup Fourth Round with a 4-0 win over Chesterfield on Tuesday night.
A first-half strike from John Swift was added to by Tom Rogic, Jake Livermore and a debut Jovan Malcolm goal after the break to secure a comfortable victory at The Hawthorns.
The Baggies will now face Bristol City in the next stage of the competition on the weekend of January 28/29.
Carlos Corberán handed a debut to Academy graduate Jamie Andrews while making 10 changes to his starting XI from Saturday’s dramatic Sky Bet Championship win at Luton Town.
And it took his team 23 minutes to open the scoring, Swift curling a fantastic effort into the top left corner from just inside the area.
Diangana very nearly doubled Albion’s advantage before half-time, too, though was denied at close-range by Spireites goalkeeper Lucas Covolan.
But they didn’t have to wait long after the interval to grab that all-important second, Albion punishing a Chesterfield mishap at the back through Rogic’s high finish - his maiden Hawthorns goal.
And the tie was effectively put beyond Albion’s non-league opponents on the 55-minute mark, Livermore hammering in to extend the hosts’ lead to three.
There were further chances at either end of the pitch – most notably Chesterfield’s Akwasi Asante hitting the crossbar and substitute Matty Phillips shooting inches wide.
Yet the fourth and final goal of the contest went to the Baggies, a special moment for Malcolm as the young striker headed past Covolan following an excellent Taylor Gardner-Hickman cross to confirm Albion's spot in Round Four and bring an end to the Spireites’ FA Cup run.
Albion: Button; Gardner-Hickman, Ajayi, Kelly, Reach; Livermore, Andrews (Townsend 61); Diangana (Wallace 76), Swift (Phillips 56), Rogic (Molumby 76); Cleary (Malcolm 61).
Substitutes: Palmer, O’Shea, Furlong, Yokuslu.