Only a couple of months ago, suggesting Liverpool would earn four successive clean sheets in the Premier League would have left you being subjected to nothing but laughter. The Reds were leaking goals left, right and centre, and the defensive issues seemed to reoccur almost every game.
Yet, after a winter revival, Brendan Rodgers' side are now looking one of the most solid defensive sides in the league - and they've done just that, recording their fourth in a 0-0 draw versus Everton on Saturday.
At least statistically speaking, Liverpool suddenly possess one of the tightest back-lines in the league. The Reds have conceded just five goals inside normal time in 10 games in all competitions, whilst they have ensured shut-outs against Everton, West Ham United, Aston Villa and Sunderland in the league. The individual errors, those that once haunted every defender in red, seem to have slowly been eased out.
Central to that has been none other than Mamadou Sakho. Thrust into playing as a left-centre back in Rodgers' trio of central defenders, he has thrived. Alongside Martin Skrtel and Emre Can, Sakho and the Reds have built solid foundations from the back and the Frenchman in particular has been given a new lease of life.
Since coming under fierce criticism from supporters and pundits in his 18 months at Anfield, Sakho has slowly began to dismiss his doubters - though there's still an argument that there is the odd nervy moment in his game here and there.
After arriving from Paris Saint Germain for £18 million, Sakho found regular first-team playing time hard to come by, due to a mix of injuries and inconsistent form. But he's been an instrumental part of the defensive solidity over the last few weeks and months.
Since coming into the starting side, Liverpool are unbeaten inside 90 minutes, keeping six clean sheets in 13 games and consequently, he's enjoying his longest streak of appearances in the team.
The youngest captain in the history of PSG, Sakho has soon started to display his best form after a difficult start to life on Merseyside. With consistent playing time, Sakho has quickly dispelled the myth that he is clumsy and prone to errors.
As rightly pointed out by Daniel Storey - last season, Liverpool committed the most individual errors of any team in the league and they paid for it, but of Sakho's only two - neither led to goals, just shots on goal. Instead it was the likes of Simon Mignolet, Martin Skrtel and Glen Johnson whose errors were costly and ended up resulting in lost points.
Another popular notion is that Sakho's figure - those long, somewhat gangly limbs - give the impression that the Frenchman is uncomfortable and awkward with the ball at his feet, whilst the truth is very much different. Sakho's passing statistics are fantastic. The 24-year-old has managed an 89% pass accuracy this season, second only to Martin Skrtel (91%) in terms of regular first-team players. In the league, of defenders who have played a minimum of 10 games, only John Terry and Skrtel's pass accuracy percentages are more accurate - whilst a further five, including Manchester City captain Vincent Kompany and Everton's Phil Jagielka, also have 89%. Sakho is no fraud.
Against Everton, quick pressing certainly exposing his nature to panic under pressure - that's fair to say. Roberto Martinez spotted a weakness and certainly exploited it, but it was a rare blemish given the composure he has displayed in games prior and the fact that it was his Merseyside derby debut, perhaps takes a little of the edge off. At the end of the day, Everton only had one real dangerous effort on target - which Simon Mignolet was equal to.
The fact that Sakho has been given only one yellow card all season after committing just six fouls (Skrtel has committed 24 in 10 more games by comparison), won over 50% of his tackles, averaged over an interception per game and has won nearly 60% of his aerial duels demonstrate that his brand of defending is clearly quite effective.
But whilst statistics, such as the one that the Reds have lost only three of the 18 games in which he played this season (and only one of those did he play the full 90 minutes) or the fact that Liverpool have committed one defensive error in the Sakho was brought back in on the December 21st - Arsenal, it is simply watching his performances that confirms he is a very good defender.
It's important to remember too, this is Sakho under a manager that only a few months ago showed very little belief in him. He stormed out of Anfield, visibly angry, at the fact he had been left out of the squad for this season's earlier Merseyside Derby. Rodgers, despite shelling out such money for him, has not always been a big believer in the Frenchman's talents, but Sakho has worked hard to change his mind.
Not only does Sakho personify leadership, he's a forward-thinking defender. As seen against Swansea City at Anfield in December, he can start attacks from the back. His long raking pass downfield set Alberto Moreno on his down the left, before his cross was eventually swept in following neat interchanging passes from Adam Lallana and Jordan Henderson.
As per, Sakho was unfairly blamed for Gylfi Sigurdsson's goal in the game. The truth though, was that Martin Skrtel was the one at fault. He did not stick close enough to Ivorian Wilfried Bony, forcing Sakho to rush across and head it away from the striker - but it unfortunately fell right into the Icelandic playmaker's path, and he rolled it into the back of the net. Yet, it was Sakho, who received the blame - whilst midfielder Henderson could equally have been attributed it for losing the ball in the centre of the park as a result of trying to be too fancy in possession.
Sakho, though, it seems - the more he plays, the more he improves. The defence is much more assured with him in it. Not only does he add leadership and exceptional vision, but he's calm, strong in the tackle, dominat in the air and has astute tactical awareness. Though, many people seem keen to ignore his qualities and criticise his pitfalls. Sakho is by no means a perfect defender. He has a few issues to iron out, issues that were shown by Everton when they forced him into rash decisions, but insisting that he lacks composure and is poor on the ball, is well wide of the mark.
Distribution-wise, Sakho is sensational - particularly in a system like Rodgers', which likes to prioritise playing out from the back. He adds both tempo and forward emphasis, and contrary to belief, is a vital part of the Reds' recent defensive solidity.
Reverting back to statistics, in the 12 matches before Sakho came into the side - Liverpool won four, lost five and kept just two clean sheets - conceding 15. In the 12 games after he came in, five clean sheets and no defeats inside normal time. Whilst that's only 24 games, which is hardly representative long-term, there's clearly a difference.
Physically imposing and powerful, yet cultured, intelligent and clever with the ball - Sakho has the perfect blend of attributes for the Premier League, and for Brendan Rodgers' Liverpool. It remains to be seen whether he can be as effective in a back two as he has been in a back three, but he certainly deserves the chance to prove his worth once the Reds abandon their stop-gap 3-4-3 system.
No-one knows what the future holds for Mamadou Sakho and his Liverpool career, but the Reds could really benefit from having the French defender in their defence for the forseeable future.