Jurgen Klopp has made many improvements to Liverpool during his time as their manager, but there is still an element of unpredictability about their displays.
When the likes of Sadio Mane, Roberto Firmino and Philippe Coutinho are on top form, they are as good as any team in the Premier League going forward.
Mohamed Salah's electric pace only adds to that, however, the major question marks which still surround the current Liverpool team are in the goalkeeping and defensive positions.
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The Reds beat Leicester City 3-2 on Saturday evening, and while the reintegration of Coutinho continues, their defence looked shaky yet again at times and Simon Mignolet made multiple errors.
Rio Ferdinand developed into a world-class defender during his time at Manchester United, so it's no surprise that he is less than impressed with Liverpool's back four.
Rio rips into two Liverpool players
Ferdinand was in the BT Sport studio for their coverage of Leicester 2-3 Liverpool, where he suggested that the Reds' ambitions of challenging for the league title this year will come unstuck due to their defensive deficiencies.
Only Leicester, West Ham and Crystal Palace have conceded more goals in the Premier League than Liverpool this term, and Rio thinks that two of their back four simply aren't good enough.
The 38-year-old, who recently announced plans to become a professional boxer, said, via Goal: "I think (Dejan) Lovren's not good enough.
"He's shown over a period of time that he makes too many mistakes. (Alberto) Moreno, defensively, is not good enough.
"Going forward he is a delight to watch, but defensively, where you want him to be good first and foremost as a defender, he doesn’t do the job, he doesn’t quite cut it."
The ex-England captain continued: "So if you’ve got two out of your back four not cutting it, you’re going to come unstuck.”
Did Liverpool get it wrong this summer?
Strong words from the Man Utd legend, but he's right in the sense that Liverpool's defence must improve if they want to have any chance of achieving success in the 2017-18 campaign.
Klopp brought in left-back Andy Robertson, but after their failed pursuit of Virgil van Dijk, he decided not to sign a centre-back, leaving them with Lovren, Joel Matip and Ragnar Klavan as their best options in that area.
Ferdinand also revealed his belief that Liverpool, who let Mamadou Sakho leave permanently this summer, would be a much better side with Van Dijk in their starting XI.
"I think Virgil van Dijk would have improved this team no end," Rio added. "He would have been that dominant centre-half and I think that, alongside Matip, that would have been a good partnership."
Do YOU agree with Rio? What do YOU think about Liverpool's current defence? Should they have signed a centre-back this summer? Was letting Sakho go the wrong decision? Leave YOUR opinions in the comments box below!