Virgil van Dijk's knee injury has "blown the title race wide open", says Sky Sports pundit Jamie Carragher, who has urged Liverpool to line up a new centre-back in January.
Liverpool defender Van Dijk will undergo surgery following a challenge by Jordan Pickford in Saturday's Merseyside derby and Carragher believes the Dutchman's absence raises real questions over whether the Reds can retain their Premier League crown.
Liverpool are currently three points behind Premier League leaders Everton.
"I think it blows the title race wide open, I really do.
"I still felt at the start of this season Liverpool were the team to beat. I think with Van Dijk being out for what looks like the whole season now, I think it's going to be all on for Liverpool. I think Liverpool certainly have to go into the market in January, and not just because of Van Dijk's injury, but Liverpool were weak in that area anyway. They lost (Dejan) Lovren before the start of the season now the other players in those positions are very injury prone.
"Yes, devastating news for Virgil van Dijk - we pass on our wishes and I'm sure everyone does around football - but I think for Liverpool, Jurgen Klopp and the club now, right away it's who can they get in?
"I know the transfer window has just finished but they have to be ready on January 2 [when the winter window opens] to bring someone in because they are really weak in that area and that could stop them going on to try to achieve what they want to achieve."
Souness: Van Dijk the one player Liverpool couldn't afford to lose
Graeme Souness also believes Van Dijk will be a huge miss for Liverpool, and argued he is the Reds' most important player.
"If you were to ask me at the start of the season, who's the one player you don't want to miss a large chunk of the season… people might say Sadio Mane, people might say Mohamed Salah… for me it's Van Dijk," said Souness. "Liverpool still have enough goals in the team to do it without one of those two.
"But at the back he's the catalyst for everything they do. From getting up the field to holding the line when it's the correct time to hold it, dropping off when it's the right time to drop off. It's a major blow. It's the last thing Liverpool needed."
In Pictures: How Van Dijk's injury happened
Souness: Pickford challenge 'an assault'
Souness was also furious at the challenge from Pickford which injured Van Dijk and could not understand how the officials had not punished the Everton goalkeeper, regardless of the offside call they had made against the Liverpool defender in the build-up.
"It amazes me," he said. "I guarantee you, every single professional who has ever played the game, semi-professional, maybe the guys on Hackney Marshes, when you look at that, the focus is not on the offside, their focus is on one thing: the assault on the player.
"It's outrageous. For me, as an ex-player, it's 'wow!'. These people who make these decisions, who sit in Stockley Park, can look at that and think, 'that's offside', I just don't get it. They just don't know what they're talking about.
"I've been to Stockley Park, it's nigh-on impossible to make a mistake with the technology they have, the time they give themselves. And they can still get it wrong.
"That wasn't a tackle, that was an assault!"
Carragher quipped: "Graeme, look at the tackles you did!"
But Souness continued: "The referee is there to protect players. Jordan Pickford didn't set out to damage Van Dijk; but if the referee doesn't see anything wrong, it then goes back to Stockley Park; if they still don't see anything wrong, that's where it's wrong.
"Anything who understands football can tell you that was a reckless challenge - I don't think Pickford meant to hurt Van Dijk badly, he's tried to make himself big - but if the ref can look at that and only wants to talk about offside, that's the problem."
Analysis: Van Dijk blow leaves Liverpool stepping into the unknown
Sky Sports' Peter Smith:
'The brilliant Dutchman has played in 95 of the 96 Premier League games Liverpool have had since he made his debut in January 2018. He played every minute in the league last season, as they claimed the title for the first time in 30 years.
'So how do they try to cover the absence of a player who has been central to their triumphs domestically and in Europe over the past three years?
'It is a huge task and, with Premier League and Champions League games coming thick and fast, it is a task Jurgen Klopp must get right if Liverpool are to continue to be successful. That is how pivotal Van Dijk has been.'
Source: Sky Sports / Jaimie Carragher