Liverpool were denied three points at Anfield as West Brom produced a brilliant second-half performance to come away from the home of the champions with a 1-1 draw.
Semi Ajayi rose highest from a West Brom corner in the 82nd minute to nod home and equaliser.
It left Jurgen Klopp and the limited number of supporters in the ground scratching their heads.
Roberto Firmino thought he had rescued all three points for the home side in the dying moments but he was denied by a superb save from Sam Johnstone.
The home side were utterly dominant, especially in the first half.
Sadio Mane fired Liverpool ahead with a wonderful finish after bringing down a through ball from Joel Matip with his chest.
Andy Robertson and Trent Alexander-Arnold were regularly marauding forward, delivering a number of dangerous balls into the box that Liverpool's forwards failed to convert.
Wasteful Liverpool
Klopp will be extremely disappointed that his team did not put the game to bed due to the number of chances his team created in the opening 45 minutes.
West Brom struggled to get out of their own half in the first period, however, they did manage to improve on that in the second half.
With 20 minutes remaining, Allardyce's men broke away on the counter-attack and Allison had to produce a save from Karlan Grant.
Liverpool had the chance to extend their lead at the top of the table and put pressure on their nearest challengers, including Manchester United and Leicester City who drew 2-2 yesterday.
Everton, who won at Sheffield United on Saturday remain in second.
The champions woes' at centre half continue to mount as Joel Matip limped off with an injury that has yet to be diagnosed.
The result means that West Brom come away from the game with a point that will boost the confidence around the club as they look to mount an escape from the relegation zone.
See what Twitter had to say to the news at full-time.
A United-Liverpool title race would have nice historical #stakes, like in 2008-09.
The battle to be the most successful ever. Liverpool hoping to equal United on 20, United looking to stay definitively ahead on 21.
I do think United will level out, and need two more players.— Miguel Delaney (@MiguelDelaney) December 27, 2020
The kind of game that underlines why Liverpool thought they needed Thiago?
— Sid Lowe (@sidlowe) December 27, 2020
FT: #LFC 1 West Brom 1: Two points carelessly squandered by the champions at Anfield. Failed to make their first-half dominance count after Mane's opener and then standards slipped dramatically in the second half. Ajayi's header restored parity. Sloppy. Matip injury a big concern
— James Pearce (@JamesPearceLFC) December 27, 2020
Simply not good enough from the Reds there 😴
— Caoimhe O'Neill (@CaoimheSport) December 27, 2020
👀
— Gary Neville (@GNev2) December 27, 2020
Liverpool far too slow with their build up play and West Brom happy to let crosses come into the box. A game crying out for Thiago but won't be long before he's back and surely Klopp has to bring in a centre half in the next few weeks.
— Phil Egan (@philegansport) December 27, 2020
Poor old Slavan Bilic stuck at home watching all this praise for Big Sam when he did the exact same thing against Man City 10 days ago!
— Nathan Murphy (@nathanmurf) December 27, 2020
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