Match ends, Liverpool 2, West Bromwich Albion 3.
Jay Rodriguez scored twice as West Brom won at Liverpool in an extraordinary FA Cup fourth-round tie dominated by video assistant referee (VAR) decisions.
Referee Craig Pawson ruled out an Albion goal, gave Liverpool a penalty and delayed awarding the visitors' third goal because of VAR referrals.
Rodriguez thumped an equaliser seconds after Roberto Firmino chipped an opener, then slotted Albion 2-1 up.
Joel Matip's own goal made it 3-1, before Mohamed Salah pulled one back.
Liverpool's first-half penalty, which Firmino missed, was a moment of VAR history - as it was the first time a referee in an English game had referred to a monitor on the touchline to make a final decision.
Pawson ruled, after a significant delay, that Jake Livermore had tugged Salah's shirt, and pointed to the spot.
Liverpool pushed hard for a late equaliser, but were poor for much of the game as they fell to their first home defeat since 23 April last year.
- Bizarre, frustrating... correct - the day VAR drove football mad
- VAR history made - Liverpool v West Brom as it happened
- What happened in the FA Cup on Saturday?
VAR takes centre stage - and causes controversy
This was only the sixth time in an English club fixture that the VAR system had been used; it proved central in a first half that was full of controversy.
The system can only be used to overturn clear cut mistakes with goals, penalties, red cards and mistaken identities - yet referee Pawson called on it three times in an opening half that ended up lasting 50 minutes.
In each case, it appeared that the right decision was reached, but the main concern for many watching was the delay in making those calls.
The biggest hold-up surrounded the penalty awarded to Liverpool midway through the first half for the foul by Livermore on Salah, with Pawson referring to a monitor at the mouth of the players' tunnel after consulting with video assistant referee Andre Marriner.
Almost three minutes passed between the initial incident and Firmino stepping up to take the penalty - with which he hit the underside of the bar.
It was the second time in a few minutes that West Brom had been on the wrong end of a VAR decision, with Craig Dawson having seen a goal ruled out that would have put them 3-1 up.
Marriner alerted Pawson to the fact that Gareth Barry, standing in front of Liverpool goalkeeper Simon Mignolet and interfering with play, was offside as Dawson headed in a Chris Brunt corner.
Just before half-time came the third use of VAR, as Dawson's cross-shot flicked in off Matip for a third Albion goal. Rodriguez had been offside earlier in the move, but did not touch the ball at any stage, and was deemed not to be interfering with play. After a hold-up while the television footage was reviewed, the goal stood.
Pawson also seemed to check with Marriner after Salah slotted in Firmino's lay-off with 12 minutes left, although there was no delay in play and no clear reason as to why the goal might have been in doubt.
Albion show spirit as Liverpool stumble
West Brom have shown significant signs of revival since ending a 21-match winless run in all competitions by winning at Exeter in the third round of the FA Cup.
Alan Pardew's side are still next to bottom of the Premier League, but are unbeaten in four matches now, winning three of them.
This was by far the most impressive of those three wins, coming despite conceding a comical opening goal after six minutes, losing left-back Kieran Gibbs and striker Hal Robson-Kanu to injury in the first half, and ending the match with only nine fully-fit players on the pitch.
Firmino chipped Liverpool in front as the ball ran loose after keeper Ben Foster had dived at the feet of Salah. The Egypt forward had snuck in as Albion captain Evans allowed a Livermore back pass to run through, unaware of the danger building.
Albion's response was outstanding; Rodriguez thumped an equaliser into the top corner 71 seconds later, then swept West Brom into a 10th-minute lead from a low Gibbs cross.
The visitors led 3-1 at half-time, following the three major VAR calls, and Salah's goal could not save Liverpool.
Jurgen Klopp's side did create a flurry of chances in the final 20 minutes, with Foster saving well from James Milner and Danny Ings, and holding onto a late glancing header from Virgil van Dijk.
But they have failed to build on the achievement of ending Manchester City's unbeaten Premier League run, with this defeat following five days after a disappointing 1-0 loss at Swansea.
Both Evans and Livermore were limping by the end, but they helped their nine fit team-mates to hold on for a win that will do much to bolster them for the task of top-flight survival.
Man of the match - Jay Rodriguez (West Brom)
West Brom match Real Madrid - the key stats
- West Brom were the first away team to score three goals in the first half at Anfield since Real Madrid did so in a Champions League match in October 2014.
- Liverpool's 19-game unbeaten home run came to an end, with this their first defeat at Anfield since a 2-1 defeat by Crystal Palace in April 2017.
- Liverpool conceded three goals in back to back home matches for the first time since January 2007.
- Jay Rodriguez has scored seven goals in his last 10 FA Cup appearances.
- Liverpool have failed to score with six of their last 10 penalties in all competitions, with four different players failing with those spot kicks (Origi, Firmino, Salah and Milner).
- There were just 71 seconds between Liverpool's first goal and West Brom's equaliser.
- West Brom have only scored more than once in three away matches this season - all have been in the cup (also 3-1 v Accrington in the League Cup and 2-0 v Exeter in the FA Cup).
- Mo Salah has had a hand in 19 goals in 17 appearances at Anfield this season for Liverpool (14 goals, five assists).
- Roberto Firmino has been involved in 16 goals in his last 15 appearances for Liverpool (11 goals, five assists).
Liverpool return to Premier League action at Huddersfield on Tuesday (20:00 GMT), 24 hours before West Brom travel to leaders Manchester City (20:00).
- 4van Dijk
- 21Oxlade-ChamberlainSubstituted forIngsat 65'minutes
- 23CanBooked at 61minsSubstituted forMilnerat 65'minutes
- 19ManéSubstituted forHendersonat 65'minutes
- 25DawsonBooked at 83mins
- 3GibbsSubstituted forHegaziat 37'minutesBooked at 85mins
- 18BarryBooked at 26minsSubstituted forYacobat 71'minutes
- 4Robson-KanuSubstituted forPhillipsat 39'minutes
- Craig Pawson
- Shots on Target
Second Half ends, Liverpool 2, West Bromwich Albion 3.
Attempt saved. Virgil van Dijk (Liverpool) header from the centre of the box is saved in the bottom right corner. Assisted by James Milner with a cross.
Attempt blocked. Mohamed Salah (Liverpool) left footed shot from the centre of the box is blocked. Assisted by Danny Ings with a headed pass.
Attempt saved. Roberto Firmino (Liverpool) right footed shot from the left side of the box is saved in the centre of the goal. Assisted by Virgil van Dijk.
Corner, Liverpool. Conceded by Ahmed Hegazi.
Attempt blocked. Virgil van Dijk (Liverpool) right footed shot from very close range is blocked. Assisted by James Milner with a cross.
Ahmed Hegazi (West Bromwich Albion) is shown the yellow card.
Corner, Liverpool. Conceded by Ahmed Hegazi.
Attempt blocked. Danny Ings (Liverpool) right footed shot from the left side of the box is blocked. Assisted by Alberto Moreno.
Craig Dawson (West Bromwich Albion) is shown the yellow card for a bad foul.
James Milner (Liverpool) wins a free kick on the left wing.
Foul by Craig Dawson (West Bromwich Albion).
Offside, Liverpool. Alberto Moreno tries a through ball, but Roberto Firmino is caught offside.
Mohamed Salah (Liverpool) wins a free kick in the defensive half.
Foul by Claudio Yacob (West Bromwich Albion).
Goal! Liverpool 2, West Bromwich Albion 3. Mohamed Salah (Liverpool) left footed shot from the centre of the box to the bottom left corner. Assisted by Roberto Firmino.
Attempt blocked. Roberto Firmino (Liverpool) right footed shot from the centre of the box is blocked.
Offside, Liverpool. James Milner tries a through ball, but Danny Ings is caught offside.
Attempt saved. Danny Ings (Liverpool) right footed shot from outside the box is saved in the bottom right corner. Assisted by Roberto Firmino.