ALBION were undone 4-1 by Leicester City in their Premier League encounter at The Hawthorns.
Salomon Rondon marked his 100th league appearance for the Baggies with an eighth-minute opener when he converted Oliver Burke's cross.
Grzegorz Krychowiak struck the crossbar as Albion looked to strengthen their advantage, only for Jamie Vardy to level for the Foxes midway through the first half courtesy of a well-taken volley over his shoulder from Riyad Mahrez's throughball.
The Algeria international then turned goalscorer just after the hour mark when he converted to put City in front, with Kelechi Iheanacho heading a third, and Vicente Iborra a fourth, in the closing stages.
Head coach Alan Pardew made two changes from the defeat at Watford, Burke and Allan Nyom coming in for Jay Rodriguez, who dropped to the bench, and Jonny Evans, struggling with illness.
Ben Foster, wearing the captain's armband, was given an early scare when his attempted clearance cannoned back off Ahmed Hegazi.
But it was Albion who broke the deadlock following a fine move down the right which saw Burke skip past Ben Chilwell and deliver an inch-perfect pacy cross for Rondon to divert home.
Vardy and Demarai Gray came close to connecting with Mahrez's deep ball before Krychowiak went closer still, his half-volley pushed on to the crossbar by Kasper Schmeichel.
Yet it was the Foxes who levelled in the 21st minute, Vardy latching on to Mahrez's long ball over the top and delivering a sublime, first-time finish into the bottom corner.
An entertaining encounter flowed from end to end, with Rondon driving at the visiting defence before seeing his strike deflected over the bar by Wes Morgan shortly before the break.
Foster reacted quickly to palm away a deflected Gray cross as the high-tempo clash remained finely poised.
Albion saw loud appeals rejected for a foul, and a possible second yellow card, as City skipper Morgan appeared to block off Rondon's run.
And within minutes the visitors took the lead when Mahrez latched on to a throughball from substitute Iheanacho and lofted the ball beyond Foster.
The Baggies No.1 raced off his line to block well from the onrushing Vardy but Leicester added a third when Iheanacho rose to head home Chilwell's cross.
Iborra added a fourth in added time, heading home a Foxes corner.
ALBION: Foster (c), Nyom, Dawson, Hegazi, Gibbs, Burke (Robson-Kanu 83), Krychowiak (Field 59), Livermore, Brunt, Phillips (Rodriguez 70), Rondon.
Subs: Myhill, McAuley, Yacob, McClean.