In an action-packed game full of drama and turning points, West Bromwich Albion managed to provide one of the shocks of the FA Cup fourth round after toppling Liverpool at Anfield - handing them their second loss in as many games across all competitions.
Things started off perfectly for the hosts, having raced into a 1-0 lead through Roberto Firmino after five minutes. Jay Rodriguez's quick-fire double was enough to see the Baggies ahead though, before Joel Matip turned the ball into his own net to gift the visitors a two-goal cushion going into the interval.
Mohamed Salah's second-half strike proved to be nothing more than a consolation in the end, as the visitors held on for a famous FA Cup triumph.
#5: The first ten minutes set the course for the entire evening
Liverpool went into the game on the back of a disappointing away defeat at the hands of Swansea last time out. Knowing it was essential to start on the right note, the Reds played their normal attack-minded brand of football, maintaining a high line while pressing their visitors' backline in the final third too.
Their hard-working attitude reaped instant rewards as a rare mistake from Jonny Evans proved enough for Salah and Firmino to capitalise to devastating effect. After Ben Foster denied Salah's initial effort, Firmino made no mistake with the rebound - a deft finish to take the lead.
However, the celebrations within a packed Anfield crowd were short-lived, as Rodriguez pulled his side back on level terms just 68 seconds later. A few minutes after the equaliser, the 28-year-old found the back of the net once again - taking advantage of a lapse in concentration from the hosts' backline to slot the ball home.
#4: First-half injuries disrupt Alan Pardew's plans
Going into the second-half with a 3-1 lead, one would expect any manager - let alone Alan Pardew - to ask his team to defend as a unit, prioritising a solid defensive display as opposed to going forward more.
However, due to the lack of reinforcements, Pardew was forced to hold off on any positional changes he perhaps would have otherwise made.
Kieran Gibbs, signed in the summer from Arsenal, sustained a hamstring injury and was unable to continue any further. Ahmed Hegazy came on in his place, being asked to play in a relatively unnatural position at left-back - unsurprisingly coming second best in his duel with compatriot Salah down the flank.
It went from bad to worse for Pardew after Hal Robson-Kanu was also forced off minutes later too with a similar injury problem. Matt Phillips replaced the Welshman, playing as their number nine - whereas he prefers playing out on the wings.
He was virtually forced into the third and final alteration in the second-half, as Gareth Barry was looking increasingly fatigued and no longer providing the Baggies with the defensive solidity he usually does. Claudio Yacob came on in his place, as their third and final substitution. Come the latter stages, both Jake Livermore and Evans also appeared to carry knocks but managed to labour on, pushing forward until the final whistle.
Had Gibbs and Robson-Kanu not have succumbed to injury, West Brom probably would have seen the game out more comfortably than they did in truth. Liverpool threatened several times during the latter stages with time running out, but the visitors edged through and booked a place in the fifth round of this year's competition.
#3: Jay Rodriguez could be the one to bail West Brom to safety
Currently, West Brom are sitting in 19th place in the Premier League and are three points away from safety. Goals have been hard to come by, which was one of the issues which ultimately led to the sacking of Tony Pulis mid-season.
Many believed their lack of clear goalscoring opportunities was down to Pulis' negative tactics, where he'd be content playing for a draw as opposed to taking more risks in the hope of all three points.
However since Pardew's arrival, he has offered players the freedom to express themselves. One player who has benefited heavily from this change in system is Jay Rodriguez.
The forward, almost forgotten, showed up at Anfield in the best way possible. Netting two early goals and silencing the capacity crowd in the process, his movement in and around the 18-yard area gave the Liverpool backline nightmares, having them constantly on their toes.
He has now been involved in five goals in as many games for the Baggies and has hit a rich vein of form at the best possible time. They face Southampton, Huddersfield, Leicester, Bournemouth and Watford in five of their next seven fixtures and he'll undoubtedly be fancying his opportunities against their defences - hoping to bail his side out of the dreaded relegation zone in the process.
#2: VAR comes to Liverpool's rescue on two occasions
Had this been a regular Premier League fixture, West Brom would have been 3-1 up and Liverpool would not have been awarded a penalty after 25 minutes. However, with there being a Video Assistant Referee (VAR), the Baggies were stripped of a goal and saw a penalty awarded against them after referee Craig Pawson took a look at the incident himself before overturning his own decision.
Craig Dawson's headed effort was chalked off after VAR was introduced - having seen the replays, it was clear that Gareth Barry appeared to be in an offside position standing just in-front of goalkeeper Simon Mignolet, while impeding the Belgian to prevent him from making a saving attempt.
Livermore and Salah battled for the ball when the Englishman's pull brought down the Liverpool forward in the box. In real time, Pawson did not spot this infringment, but after having multiple glances at the incident again, he decided a penalty was awarded.
West Brom players felt it was a harsh decision and were understandably overjoyed when Firmino's spot-kick hit the crossbar, consequently keeping their lead intact.
#1: A £75 million acquisition but defensive woes persist for Liverpool
While the critics were quick to judge the eyewatering cost of Virgil van Dijk's move to Liverpool, there were no real doubts surrounding the Dutchman's abilities. Having proved himself at Southampton, it appeared now was the right time for him to make the leap into European football once more - representing a club of Liverpool's stature and quality.
Plenty of fanfare surrounding his arrival at Anfield earlier this month and they saw his signing as the beginning of the end in terms of their defensive woes. Little did they know what the near future had in store for them.
West Brom - who are notorious for their defensive qualities - managed to breach the Liverpool backline and score on three separate instances in the first-half. All of the goals themselves could have been dealt with, had the defenders organised themselves more effectively. Due to the lack of leadership though, it all fell apart for the Reds.
Jurgen Klopp must know by now that buying a quality defender and failing to put in the hard work on the training pitches by working on defensive positioning within the squad is not going to reap long-term benefits. The German has to stress the importance of maintaining shape to his side, and could possibly look to alter his tactics in future if his defenders are continually incapable of this.