Virgil van Dijk versus Romelu Lukaku reminds us of the irresistible force paradox: the immovable object in Liverpool's defence meeting the unstoppable might of Chelsea's centre forward.

It makes Saturday's clash at Anfield an unmissable prospect for fans of conflict between tall men from the Low Lands.

Van Dijk was sorely missed as he sat out almost all of Liverpool's title defence season last term, when a series of shattering injury blows to the Reds backline left Jurgen Klopp severely hamstrung.

The Dutch powerhouse has recovered from knee surgery and is back at the heart of manager Klopp's defence, striving for full match fitness, while Lukaku has returned to the Premier League after two years at Inter.

Their much-anticipated tussle this weekend could tell us a lot about the Premier League title prospects of Liverpool and Chelsea this term.

Is Van Dijk physically ready?

Lukaku seized on weakness in the Arsenal defence last weekend to get off the goalscoring mark in his Chelsea career, a decade on from making his debut in a short-lived first spell at Stamford Bridge.

He hit the crossbar with a header too, as the Gunners failed to contain his threat, the Belgian's intelligent movement and physical prowess proving more than Arsenal could contain. He had eight goal attempts, a single-match total that has only been beaten six times in the two years and two weeks between his move to Inter and his Premier League comeback.

It adds up to trouble for Liverpool if Van Dijk is short of his best, and if facing Burnley last week in his second Premier League game was a gauge of where he is at, then there might be questions to ask.

Van Dijk was involved in 12 aerial duels and won just five of those, or 41.7 per cent. That is way down on his league average of 74.3 per cent since the beginning of the 2018-19 season, his first full campaign at Liverpool, Van Dijk winning 393 of 529 such battles in the air.

His passing accuracy of 80.77 per cent was also significantly below par, with Van Dijk only ever having dipped below that 11 times in the league since joining Liverpool in the January 2018 transfer window. Curiously it had happened twice previously against Burnley, perhaps pointing to a certain discomfort when facing the Clarets.

How has United misfit become a hotshot?

Lukaku scored 16 Premier League goals for Manchester United in 2017-18 from an expected goals (xG) tally of 13.43, and 12 from an xG of 10.67 in the following season. He then took his trade to Italy and netted 23 times in Serie A from an xG of 18.85 in 2019-20 before striking 24 times (xG 23.75) in Inter's Scudetto-winning 2020-21 campaign.

His shot conversion rate has climbed incrementally from 18.5 per cent in 2017-18 to 25 per cent last season, and he is a player whose confidence is soaring.

A big chance conversion rate of 39.29 per cent across all competitions in his final season at United was Lukaku's worst since the 2012-13 campaign (37.5 per cent). By improving to 46.51 per cent and then 51.02 per cent in his two years at Inter he was not tucking away those big chances – defined by Opta as situations 'where a player should reasonably be expected to score' – at an outlandish rate, but those are healthy enough numbers.

To take the example of his final season at Everton, the 2016-17 campaign, Lukaku had a big chance conversion rate of 73.08 per cent. That is his capability, which few can hope to match.

Lukaku certainly believes he has returned to England an improved player, and his 11 assists in Serie A last season reflect well in that aspect. In 2018-19 at United, he had no assists, although in the previous campaign he managed seven.

Dribble trouble for Van Dijk?

Lukaku has found his dribbling boots again too, and that has to be bad news for Premier League defences. In his three dazzling seasons at Everton, Lukaku chalked up 105, 87 and 104 attempted dribbles while on Premier League duty, but his totals fell away to 63 and then 41 while at United. Stymied either by the role he was being asked to play, or by his waning spirits, an important part of Lukaku's game went AWOL.

He attempted just 45 dribbles in his first Serie A campaign too, but that shot up to 103 in 2020-21, and the sight of an eager Lukaku with the ball at his feet is a worry for any defender, even one Van Dijk's pedigree.

Famously, Van Dijk is rarely dribbled past by opponents. Since his Liverpool debut in January 2018, he has only been beaten in such a way eight times in the Premier League, the fewest of all defenders with at least 50 games behind them over that time.

Still the full package?

"The package of Virgil van Dijk is really helpful," said Klopp after Liverpool battled to their 2-0 win over Burnley.

Unmistakably true, and the centre-back belongs to the calibre of player that can raise their game to another level when presented with a major challenge. It is why Liverpool spent £75million to bring him in from Southampton. When many thought they were paying over the odds, Liverpool were certain he would take them up a level, and duly he has.

The character and presence of the 2019 Ballon d'Or runner-up can influence those around him, even when the data suggests he is performing, act for act, below his peak levels.

There is no doubt Van Dijk will relish the challenge presented by Lukaku, despite having played on a losing team against Chelsea's new number nine before, notably when United edged Liverpool 2-1 at Old Trafford in March 2018, as Marcus Rashford's double made the difference.

Saturday's tussle is one between elite-tier Premier League stars, and immovable versus unstoppable is an absurdity that adds up to stalemate.

That may be how Lukaku versus Van Dijk plays out, the match won or lost elsewhere while they scrap out their own spectacular sideshow, two colossi on whom so much will depend over the next nine months.