Albion produced an all-action display to secure an emphatic and well-deserved victory against Chelsea at Stamford Bridge on Saturday afternoon.
The hosts seized the initiative through Christian Pulisic, but a Thiago Silva red card helped turn the game on its head as Albion took full advantage.
Matheus Pereira's quick-fire double right at the end of the first half gave the Baggies the lead, before substitute Callum Robinson netted a brace either side of Mbaye Diagne and Mason Mount efforts in the second half to secure an emphatic, morale-boosting win in the capital.
Albion started strongly and had a couple of opportunities to open the scoring early on, Pereira side-footing straight at Edouard Mendy before seeing a free-kick well blocked.
Yet, with their first real chance, it was Chelsea who took the lead on 27 minutes. Marcus Alonso’s free-kick came back off the post and fell to Pulisic, and the American international made no mistake in tucking home the rebound.
Almost immediately the hosts were reduced to 10 men when Silva was shown a second yellow card for a follow-through on Okay Yokuslu.
And The Baggies made the most of their numerical advantage ahead of half-time as Pereira netted twice to turn the game around - his first a superb dink over Mendy after latching onto Sam Johnstone’s ball forward, the second a very clever effort following quick build-up play around the Blues’ box.
The clash continued in the same vein at the start of the second period, with the sides exchanging blows in search of that crucial fourth goal.
Alonso hit the post and Kurt Zouma volleyed off-target for Thomas Tuchel’s team - however Albion were the ones to score next through substitute Robinson’s fantastic volley. The strike was his first since notching against Chelsea back in September.
Diagne then finished off a brilliant move involving Conor Townsend and Pereira from the edge of the area to make it four and send the Baggies into dream land on 68 minutes.
The Blues soon got back in it thanks to Mount’s close-range conversion but the Baggies weren't finished there.
More late pressure was rewarded when Robinson beat the offside trap to run onto Pereira's through ball in behind to lob over a stranded Mendy, netting Albion's fifth of the afternoon to consolidate a thumping three points.
Albion: Johnstone, Furlong, O’Shea (Ivanovic 24, Robinson 37), Bartley, Ajayi, Townsend; Phillips (Livermore 89), Yokuslu, Maitland-Niles; Pereira, Diagne.
Substitutes: Button, Peltier, Snodgrass, Diangana, Grant, Robson-Kanu.