How it must hurt. To be 2-1 up and be in with a very good chance of recording a first win since February only to have it snatched away.
Danny Cowley had watched his side take the lead, be pegged back and then take the lead once more. His Huddersfield side had worked tirelessly to keep their shape, stay compact and tough to get past.
But Grady Diangana, on loan from West Ham, would take it all away with just two kicks of the ball. Cowley could only put his hands behind his head as Diangana delivered the most inviting of crosses which Darnell Furlong headed in off Kamil Grabara’s right post.
Matt Phillips scored a brace in West Brom's 4-2 win over Huddersfield at The Hawthorns
West Brom's No 10 finished off a brilliant run from Grady Diangana (not pictured) to score
Phillips (left) celebrates with Diangana (R) after scoring his brace to give West Brom the lead
WEST BROM: (4-2-3-1) Johnstone 6; Furlong 6.5, Ajayi 7, Bartley 5.5, Ferguson 6.5; Livermore 6, Sawyers 6; Phillips 7 (Robson-Kanu 81), Krovinovic 6.5 (Diangana 46, 8), Pereira 7; Austin 7 (Zohore 72, 6)
SUBS NOT USED: Bond (GK); Brunt, Edwards, O'Shea
GOALS: Phillips (19, 75), Darnell Furlong (70), Ajayi (89)
COACH: Slaven Bilic 7
HUDDERSFIELD: (4-3-3) Grabara 6; Hadergjonaj 6, Elphick 7, Schindler 7, Kongolo 5 (Brown 63, 6); Chalobah 6, Hogg 6, O’Brien 7 (Diakhaby 83); Kachunga 7, Campbell 6.5 (Mounie 65, 6), Grant 7
SUBS NOT USED: Schofield (GK); Bacuna, Mbenza, Stankovic
GOALS: O'Brien (16), Ahearne-Grant (36)
COACH: Danny Cowley 6
REFEREE: Tim Robinson 6
MAN OF THE MATCH: Grady Diangana (West Brom)
VENUE: The Hawthorns
Five minutes later, and with 15 minutes to play, Diangana produced the game’s biggest moment. He wriggled clear of Jonathan Hogg, Trevoh Chalobah and Florent Hadergjonaj.
He then turned inside, spotted Matt Phillips and supplied him with a pass that the winger guided past Grabara. By the time Semi Ajayi headed in Matheus Pereira’s corner for West Brom's fourth, it was, in fairness, all over.
It was devastating for Huddersfield and that run without a win goes on. Nineteen matches now without one and this makes it five defeats in five. Bottom of the league with just one point to their name.
For West Brom, while it may have taken a while, this was proof of just how ferocious and dangerous they can be.
Slaven Bilic’s side remain the only unbeaten team in the Championship and a current position of fourth in the league – one point off top – is a fair reflection.
Huddersfield knew they would be up against it. But there is perhaps nobody who wants them to get out of the rut they currently find themselves in than Lewis O’Brien.
O’Brien, a busy tackling midfielder, is 20 but knows he has just as an important job to do as the rest of his team-mates.
He was successful in preventing two West Brom attacks in the first 10 minutes.
First he stopped Phillips breaking clear before cutting out a pass that looked destined to set Charlie Austin free through the centre.
Lewis O'Brien breaks the deadlock with a brilliant left-footed strike to give Terriers' the lead