Marcelo Bielsa's Leeds United lost ground at the top of the Championship as West Brom ran riot in the second half to earn a 4-1 win at The Hawthorns.
With Norwich City having beaten Millwall 4-3 earlier on Sunday (AEDT) to go three points clear at the top, Bielsa's side required victory to move into pole position.
But it was West Brom who deservedly took the spoils from an action-packed encounter, Darren Moore's side – who had hit the woodwork through Jay Rodriguez in the first half – carving Leeds' defence open at will after the interval.
Hal Robson-Kanu got the rout started, slotting home at the culmination of a slick counter-attack after Leeds' Kemar Roofe had a penalty appeal turned down at the other end.
Harvey Barnes squandered a brilliant opportunity to double the hosts' lead shortly after, but the Baggies had their second when Bailey Peacock-Farrell failed to deal with Matt Phillips' speculative effort.
Barnes made up for his earlier miss in the 82nd minute, racing clear before lifting a delicate lob over Peacock-Farrell, who was beaten again a moment later when Dwight Gayle rounded off a brilliant West Brom performance with a clever back-heel, although Pablo Hernandez did head in a stoppage-time consolation.
The victory ends West Brom's four-match winless streak, lifting them up into fifth, while Leeds sit in third.