It is December 16, 2018 – Liverpool have just beaten Manchester United 3-1 at Anfield in Jose Mourinho's final match in charge of the Red Devils.

Victory sends Liverpool to the top of the Premier League, and while they ultimately narrowly missed out on the title that season, hindsight shows it was a signpost for their potential and depths United have plumbed.

Ole Gunnar Solskjaer came in soon after on an interim basis and, despite there being critics who consistently call his abilities into question, there can be no doubt of the impact he has had.

Sunday January 17, 2020 – United go to Anfield top of the Premier League, three clear of their bitter rivals. It is an achievement in itself, though Solskjaer has taken every opportunity to play it down – his terse response when asked in his pre-match news conference if he had received messages of congratulations from former team-mates highlighted his indifference.

After all, in an ideal world for United, this is just the start – they must now look to make the summit their permanent residence in the table and continue to develop.

While Solskjaer would surely not say so publicly, there is one area in particular where United should seek inspiration from their old nemesis.

FULL-ON FULL-BACKS

One of the Liverpool's greatest strengths over the past few years on their ascension back to the top of the pile in English football has been their first-choice full-backs.

Generally speaking, it is quite rare for a side to have a right-back and left-back who are both effective at either end of the pitch, yet Andy Robertson and Trent Alexander-Arnold are just that, and especially so from an offensive perspective.

They can help to create overloads in attack, with their presence in the final third still ensuring they carry a threat out wide even if the likes of Sadio Mane and Mohamed Salah have tucked inside, as they frequently do.

It's difficult to say United find themselves in a similar situation, however.

Luke Shaw has demonstrably improved as an attacking presence, suggesting the signing of Alex Telles motivated him to work harder.

The left-back is producing more crosses, successful crosses, key passes and passes into the box than he was last season, whereas Aaron Wan-Bissaka has regressed in each of those areas.

A reported £50million signing from Crystal Palace in 2019, Wan-Bissaka was billed as potentially United's right-back for the next decade, but at the moment he looks out of place in a team that generally attacks with speed, precision and commitment.

WAN-BISSAKA'S REGRESSION

Of course, a full-back's primary function is – for the most part – to defend, but as champions Liverpool prove, having players comfortable with both sides of the game provides a real advantage.

Wan-Bissaka certainly did not look to be a lost cause last season – his tally of three open-play crosses per game, while not outstanding, at least showed a desire to get forward. This season, there are only 13 players who have featured at least 10 times in the league to have averaged more than three.

But in 2020-21, Wan-Bissaka's numbers have shot down. Now he is delivering just 1.1 crosses per 90 minutes and his overall key passes total of eight only puts him level with United's back-up left-back Telles, who has played just six games.

Robertson leads the way among defenders with 32, while Alexander-Arnold, Joao Cancelo and Aaron Cresswell have 25 each, and next is the improved Shaw on 22.

UNBALANCED UNITED

So, what does this mean for United?

Above all it contributes to them being lopsided. It's no secret that they have issues on the right side of their attack, with Anthony Martial and Marcus Rashford both preferring to operate from the left if not through the middle, while Mason Greenwood simply hasn't managed to recapture his form from last term yet.

This arguably makes it even more important to have a presence on the right, but seemingly Wan-Bissaka's team-mates do not have the same kind of trust in him as they do Shaw and Telles on the left.

Just 33 per cent of United's passes from the wing into the box this season have come from the right flank, which means they go down the left about twice as often.

There is no such disparity for Liverpool, though.

Even in a season when Alexander-Arnold's level is being criticised, Liverpool still frequently look to try their luck down the right.

In fact, 52 per cent of their passes from the wing into the opposing penalty area have been from his side of the pitch. They have much greater balance, and therefore this ensures they are less predictable.

Of course, this isn't just on Wan-Bissaka. As mentioned, it highlights an overriding issue with United's right wing, but it does also raise questions about whether they feel he is their best bet long-term at right-back.

In Wan-Bissaka's first season, his remarkable tackling numbers – which do remain impressive this term – and effort to get forward fairly frequently showed promise, even if some fans expected more from a £50m full-back.

But with United hoping this is the start of them establishing themselves among the leading powers of English football once again, there's little doubt a right-back with greater attacking presence would offer them another dimension.