ALBION secured a memorable 3-2 triumph over Liverpool in an incident-packed FA Cup fourth-round tie at Anfield.
Three goals in the first 11 minutes lit the blue touch paper for a dramatic and extraordinary Saturday night on Merseyside, Jay Rodriguez scoring twice to cancel out Roberto Firmino's opener.
VAR was then used on three occasions in the first half - firstly to rule out Craig Dawson's header for offside before the Reds were awarded a penalty after Jake Livermore was adjudged to have pulled back Mohamed Salah, only for Firmino to smash the resulting spot-kick against the crossbar.
The Video Assistant Referee was then again called upon to confirm Albion's third goal on the stroke of half-time was not offside, Joel Matip putting into his own net from close range.
Salah's 78th-minute strike added further drama to a thrilling five-goal cup tie but it was the Baggies who secured their place in the fifth round of the competition - ending Liverpool's 19-match unbeaten record on home soil.
The superb result puts Albion into Monday's draw for the last 16 and continues their fine form under Head Coach Alan Pardew, with just one defeat in their last seven.
A pulsating start to proceedings saw the visitors come from behind to lead 2-1 with just 11 minutes on the clock.
Firmino chipped over Ben Foster following a defensive mix-up with captain Jonny Evans in the fifth minute, before Rodriguez bagged a four-minute brace to put the Baggies in front - making it five goals in his last six matches.
His first was a stunning finish into the top corner from just inside the area, leaving Simon Mignolet with no chance, before slotting home Kieran Gibbs' low cross to turn the game on its head.
Yet that was just an appetiser for the 53,342 inside Anfield as VAR took centre stage on a dramatic evening.
Dawson celebrated a header he thought had made it 3-1, only for the effort to be ruled out upon consultation with the Video Assistant Referee, Gareth Barry adjudged to be offside.
There was even more drama shortly after as - for the first time in English football - referee Craig Pawson himself viewed a video replay pitchside to deem Livermore tugged back Salah.
Yet Firmino struck the underside of the crossbar with the resulting spot-kick.
Albion lost Gibbs and Hal Robson-Kanu to injury within minutes of each other before VAR was used again to determine a crucial moment in the tie.
Dawson was deemed to be onside when he collected a high ball, played across the face of goal and Matip put through his own net from close range.
Dawson was at the centre of matters again soon after the second half restarted, seeing his header ruled out for offside.
Albion were indebted to Foster for making stunning saves to deny substitutes James Milner and Danny Ings.
However, he was powerless to prevent Salah from reducing the arrears in the 78th minute as he slotted home a loose ball in the penalty area.
Yet the strike proved mere consolation as Albion supporters celebrated a super victory in a cup tie that will live long in the memory, chanting "there's only one Cyrille Regis".
ALBION: Foster, Nyom, Dawson, Evans (c), Gibbs (Hegazi 37), Livermore, Barry (Yacob 71), Krychowiak, Brunt, Robson-Kanu (Phillips 39), Rodriguez.
Subs: Myhill, Yacob, McClean, Burke, Rondon.