Divock Origi's deflected 95th-minute strike rescued a point for Liverpool against a resolute West Brom.
The home side began well and took the lead when Jordan Henderson finished a superb and patient passing move.
But Simon Mignolet's error gifted a goal to Craig Dawson of Albion, who were furious when a delayed offside flag denied Jonas Olsson a goal.
Olsson looked to have headed West Brom to victory before substitute Origi's shot found the net deep in added time.
Such was the relief around Anfield at full-time that Reds manager Jurgen Klopp called his entire team together to conduct on-field celebrations in front of the Kop.
The point earned means Liverpool are ninth in the table, five points off the top four, while the two points lost leave West Brom 13th, six points above the bottom three.
Striker Origi joined Liverpool in July 2014 for £10m but spent his first season on loan at Lille and has started only two league games this campaign.
However, after scoring a hat-trick in this month's 6-1 demolition of Southampton in the Capital One Cup, he now has a first, memorable league goal for the Reds, coming in the fifth of eight minutes added for a serious leg injury to defender Dejan Lovren, resulting from a tackle with Craig Gardner.
It came at the end of a game the home side largely dominated, both in terms of possession and shots.
Klopp's side had 70% of the ball, 28 attempts at goal to the Baggies' four and produced the goal of the game - a superb opener that began with goalkeeper Mignolet, comprised 20 passes and ended with Henderson firing home first time from Adam Lallana's downward header.
That Liverpool were forced to chase the game is down to a significant error from their goalkeeper, their own wastefulness in front of goal and West Brom's resilience.
Mignolet would undermine his side's good work soon after Henderson's opener with an air-punch from a corner that allowed Dawson to finish from close range.
With Liverpool's confidence visibly dented, West Brom took advantage and went ahead through Olsson's glancing header from a Chris Brunt corner.
However, during the course of the game, the home side had enough chances to win.
Between them, Philippe Coutinho and Christian Benteke had 10 shots, with the former firing the best of them over from 15 yards, while Lallana was denied by Boaz Myhill after breaking through the Baggies defence.
While the second half ended in drama, the first concluded in controversy.
West Brom thought they would be heading into the break in front after Olsson had volleyed home a Craig Gardner free-kick from close range. Indeed, the Baggies players managed a good 30 seconds of celebration before they were cut short by an extremely belated flag for offside.
Replays had shown the ultimate decision to be the right one but Albion manager Tony Pulis and his players were irate at the mysterious and protracted manner in which it was reached.
Liverpool manager Jurgen Klopp: "I'm satisfied now because it was the perfect finish to this game. The one point was the minimum that we deserved today.
"Two set plays cost us. We knew about their quality in these situations. It was difficult. We created chances, made a perfect goal then conceded those two.
"But at the end I can live with it. This could prove to be a very special moment for us in the season to strike back against such a team."
West Brom manager Tony Pulis: "We're disappointed. We showed great resilience and to get done with a deflected goal in the eighth minute of stoppage time is particularly disappointing for the players.
"I can't fault the players. To come to a place like this with their budget, players and standing, we shouldn't be in their league."
On Albion having a goal ruled out for a 2-1 lead before half-time: "What disappointed me is the linesman doesn't put his flag up. If he puts his flag up straight away it is offside. Why the referee goes over and talks to him I don't know."
Liverpool travel to Watford next Sunday for a 13:30 GMT kick-off in the Premier League, while West Brom's final fixture before Christmas is at home against in-form Bournemouth on Saturday.
Full Time Match ends, Liverpool 2, West Bromwich Albion 2.
90:00 +9:29 Full timeFull Time Second Half ends, Liverpool 2, West Bromwich Albion 2.
90:00 +8:01Attempt blocked. Nathaniel Clyne (Liverpool) right footed shot from outside the box is blocked. Assisted by Emre Can.
90:00 +5:24 Goal scoredGoal! Goal! Liverpool 2, West Bromwich Albion 2. Divock Origi (Liverpool) right footed shot from outside the box to the bottom right corner. Assisted by Jordan Henderson.
90:00 +4:36Corner, Liverpool. Conceded by James Morrison.
90:00 +3:38 SubstitutionSubstitution Substitution, West Bromwich Albion. Rickie Lambert replaces Salomón Rondón.
90:00 +2:35Corner, Liverpool. Conceded by Craig Dawson.
90:00 +2:33Attempt blocked. Divock Origi (Liverpool) right footed shot from the left side of the box is blocked. Assisted by Christian Benteke.
90:00 +2:02Simon Mignolet (Liverpool) wins a free kick in the defensive half.
90:00 +2:02Foul by Salomón Rondón (West Bromwich Albion).
90:00 +0:01Foul by Christian Benteke (Liverpool).
90:00 +0:01Jonas Olsson (West Bromwich Albion) wins a free kick in the defensive half.
88:59Attempt missed. Jordon Ibe (Liverpool) left footed shot from outside the box is close, but misses to the right. Assisted by Alberto Moreno.
88:14Attempt saved. Jordan Henderson (Liverpool) right footed shot from outside the box is saved in the top centre of the goal. Assisted by Jordon Ibe.
86:39Attempt missed. Salomón Rondón (West Bromwich Albion) right footed shot from outside the box is close, but misses to the left. Assisted by James McClean.
85:33Attempt blocked. James Milner (Liverpool) right footed shot from outside the box is blocked. Assisted by Alberto Moreno.
85:03 SubstitutionSubstitution Substitution, Liverpool. Roberto Firmino replaces Adam Lallana.
84:36Hand ball by Craig Gardner (West Bromwich Albion).
83:34Attempt blocked. James Milner (Liverpool) right footed shot from outside the box is blocked.
82:16Attempt blocked. Alberto Moreno (Liverpool) left footed shot from outside the box is blocked.
Attempt saved. Adam Lallana (Liverpool) right footed shot from the centre of the box is saved in the centre of the goal. Assisted by Christian Benteke.
78:26 SubstitutionSubstitution Substitution, Liverpool. Divock Origi replaces Dejan Lovren because of an injury.
78:22Delay over. They are ready to continue.
74:33Delay in match Dejan Lovren (Liverpool) because of an injury.
72:37 Goal scoredGoal! Goal! Liverpool 1, West Bromwich Albion 2. Jonas Olsson (West Bromwich Albion) header from the right side of the six yard box to the bottom left corner. Assisted by Chris Brunt with a cross following a corner.
71:58Corner, West Bromwich Albion. Conceded by Emre Can.
71:01 SubstitutionSubstitution Substitution, Liverpool. Jordon Ibe replaces Philippe Coutinho.
70:29Delay over. They are ready to continue.
69:20Delay in match James Milner (Liverpool) because of an injury.
66:47Christian Benteke (Liverpool) wins a free kick in the attacking half.
66:47Foul by Jonny Evans (West Bromwich Albion).
65:01Simon Mignolet (Liverpool) wins a free kick in the defensive half.
65:01Foul by Darren Fletcher (West Bromwich Albion).
64:21Corner, West Bromwich Albion. Conceded by Dejan Lovren.
63:38Delay over. They are ready to continue.
62:35Delay in match Gareth McAuley (West Bromwich Albion) because of an injury.
61:29Attempt blocked. Jordan Henderson (Liverpool) right footed shot from outside the box is blocked. Assisted by Nathaniel Clyne.
60:51Attempt missed. Christian Benteke (Liverpool) right footed shot from the centre of the box misses to the right.
58:28Attempt missed. Jordan Henderson (Liverpool) right footed shot from outside the box is too high. Assisted by Emre Can.
55:47Alberto Moreno (Liverpool) wins a free kick in the defensive half.
55:47Foul by Salomón Rondón (West Bromwich Albion).
54:33Foul by Martin Skrtel (Liverpool).
54:33Gareth McAuley (West Bromwich Albion) wins a free kick in the defensive half.
53:58Corner, Liverpool. Conceded by Gareth McAuley.
53:56Attempt blocked. Dejan Lovren (Liverpool) header from the centre of the box is blocked. Assisted by James Milner with a cross.
53:14Adam Lallana (Liverpool) wins a free kick in the attacking half.
53:14Foul by Jonas Olsson (West Bromwich Albion).
51:24Attempt missed. Christian Benteke (Liverpool) header from the centre of the box is high and wide to the right. Assisted by Alberto Moreno with a cross.
50:10Attempt missed. James Milner (Liverpool) right footed shot from outside the box is close, but misses to the left. Assisted by Philippe Coutinho.
47:30Foul by James Milner (Liverpool).
47:30Craig Gardner (West Bromwich Albion) wins a free kick in the defensive half.
46:27Adam Lallana (Liverpool) wins a free kick in the attacking half.
46:27Foul by Jonas Olsson (West Bromwich Albion).
45:00Second Half begins Liverpool 1, West Bromwich Albion 1.
45:00 +1:36 Half timeHalf Time First Half ends, Liverpool 1, West Bromwich Albion 1.
45:00 +0:06Offside, West Bromwich Albion. Craig Gardner tries a through ball, but Jonas Olsson is caught offside.
44:30Foul by Emre Can (Liverpool).
44:30Darren Fletcher (West Bromwich Albion) wins a free kick in the attacking half.
43:47Attempt missed. Jordan Henderson (Liverpool) right footed shot from outside the box is high and wide to the right. Assisted by James Milner.
42:13Attempt missed. James Milner (Liverpool) left footed shot from the right side of the box is high and wide to the left. Assisted by Adam Lallana.
39:31Attempt saved. Philippe Coutinho (Liverpool) right footed shot from outside the box is saved in the bottom right corner. Assisted by Dejan Lovren.
37:46Attempt missed. Christian Benteke (Liverpool) right footed shot from the centre of the box is close, but misses to the left. Assisted by Alberto Moreno.
37:02Christian Benteke (Liverpool) wins a free kick in the attacking half.
37:02Foul by Gareth McAuley (West Bromwich Albion).
34:58Dangerous play by Martin Skrtel (Liverpool).
34:58Salomón Rondón (West Bromwich Albion) wins a free kick in the attacking half.
33:19Attempt saved. Philippe Coutinho (Liverpool) right footed shot from outside the box is saved in the bottom left corner. Assisted by Emre Can.
32:58Alberto Moreno (Liverpool) wins a free kick in the defensive half.
32:58Foul by Craig Gardner (West Bromwich Albion).
29:51 Goal scoredGoal! Goal! Liverpool 1, West Bromwich Albion 1. Craig Dawson (West Bromwich Albion) left footed shot from very close range to the bottom left corner. Assisted by Salomón Rondón following a corner.
28:46Corner, West Bromwich Albion. Conceded by James Milner.
27:57Attempt missed. James Morrison (West Bromwich Albion) left footed shot from the centre of the box misses to the right.
27:01Attempt saved. Philippe Coutinho (Liverpool) right footed shot from outside the box is saved in the centre of the goal. Assisted by Emre Can.
25:38Christian Benteke (Liverpool) wins a free kick in the attacking half.
25:38Foul by Gareth McAuley (West Bromwich Albion).
25:05Attempt blocked. Christian Benteke (Liverpool) right footed shot from the left side of the box is blocked. Assisted by Philippe Coutinho.
20:50 Goal scoredGoal! Goal! Liverpool 1, West Bromwich Albion 0. Jordan Henderson (Liverpool) right footed shot from the centre of the box to the centre of the goal. Assisted by Adam Lallana with a headed pass.
18:23Corner, West Bromwich Albion. Conceded by Simon Mignolet.
17:40Dangerous play by Emre Can (Liverpool).
17:40Salomón Rondón (West Bromwich Albion) wins a free kick in the attacking half.
16:33Attempt missed. Christian Benteke (Liverpool) header from very close range misses to the right. Assisted by Alberto Moreno with a cross.
13:03Attempt missed. Philippe Coutinho (Liverpool) right footed shot from the centre of the box is too high.
11:43Offside, Liverpool. Dejan Lovren tries a through ball, but Adam Lallana is caught offside.
10:37Attempt saved. Emre Can (Liverpool) left footed shot from a difficult angle on the left is saved in the bottom left corner.
9:53Corner, Liverpool. Conceded by Gareth McAuley.
9:51Attempt missed. Nathaniel Clyne (Liverpool) right footed shot from outside the box misses to the left.
9:47Attempt blocked. Christian Benteke (Liverpool) right footed shot from outside the box is blocked. Assisted by Adam Lallana.
1:29Foul by Emre Can (Liverpool).
1:29James Morrison (West Bromwich Albion) wins a free kick in the defensive half.
0:00First Half begins.
0:00Lineups are announced and players are warming up.
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