Opinion: Returning Fabinho and Matip have been excellent, but they must earn their recalls
(Photo by Nick Taylor/Liverpool FC/Liverpool FC via Getty Images)

It is testament to Liverpool's strength-in-depth that their title march has maintained its extraordinary momentum even after injuries to two world-class players. 

Fabinho, arguably the best midfield anchor in the world in 2019, has been out since the end of November when he damaged ankle ligaments against Napoli in the Champions League.

Joel Matip, who was performing at the same level as the benchmark-setting Virgil van Dijk, has been missing even longer, his last appearance coming at Old Trafford on the one and only occasion thus far when Liverpool have dropped points.

But with Sky Sports confirming on Wednesday that the pair had returned to training, they can be labelled 'back in contention ahead of the visit of arch-rivals Manchester United on Sunday. 

Fabinho must displace magnificent Henderson

On the face of it, a player of Fabinho's calibre would stroll back into the team. More recent injuries to James Milner and Naby Keita have left Liverpool short of numbers in midfield, and he is not in direct competition with the attack-minded Alex Oxlade-Chamberlain and Adam Lallana.

But the form of newly-crowned England Player of the Year Jordan Henderson has complicated matters somewhat.

At the back end of last season, Henderson was shuffled into a more advanced role, and his reinvigorated performances seemed to suggest he had found a new home, Jurgen Klopp indicating an eagerness to accommodate the skipper without dropping master-of-his-craft Fabinho.

This season, the reverse has occurred. Henderson's displays in the more offensive position settled to the level of solid, but uninspiring, and then, when he was restored to the deeper role in the wake of Fabinho's injury, he found another level.

In fact, the 29-year-old has carried out the task with such distinction that the acclaim of the footballing world has reached an all-time high. Suddenly pundits are pondering whether he has been criminally underrated, and his name is cropping-up among European football's midfield elite. 

Moreover, with Henderson acting as the shield, Liverpool's defence has enjoyed a spectacular upsurge in clean sheets. 

The Reds were without Fabinho for the season's most intense period, but they shipped only four goals over the relentless succession of fixtures (discounting those allowed by the Under-23s against Aston Villa). They have kept six clean sheets in a row for the first time in more than 13 years.

The inclusion of these figures is in no way meant as a slight against Fabinho - he certainly did not appear to be central to his side's relative defensive frailty - but they are meant to emphasise Klopp's dilemma.

A fresh positional change for Henderson risks disrupting the captain's imperious rhythm. Does the manager take that chance to ensure a swift reintegration for Fabinho, or does he continue with a Henderson-Wijnaldum-Oxlade-Chamberlain/Lallana trio for the moment?

Fabinho must convince him of the possibility of a seamless transition.

For Matip, the boot is on the other foot

Rewind nearly a year, and you would observe at a remarkably similar scenario, albeit with interchanged personnel. Joe Gomez is in the form of his life, and then he sustains a serious injury. Joel Matip deputises to such great effect that he locks down a starting role until the end of the campaign, with Gomez consigned to the fringes upon his return.

Matip had a truly outstanding 2019, but now it is he who faces the prospect of serving as understudy for the remainder of the campaign following a spell on the sidelines. 

Gomez, jittery in earlier routings, has made himself undroppable, reforming a partnership with Van Dijk scarcely matched, if at all, in its solidity. 

Individually, there is very little to separate Gomez and Matip at their respective peaks, but it is hard to ignore the fact that the Liverpool defence has re-established itself as the division's best in the sustained presence of the former.

Rotation will play its part of course, but it would take errors from the usually domineering Gomez to overhaul the present pecking order and alter Klopp's conception of his strongest team.

To indulge the cliche, though, this presents a welcome headache for the manager as his squad edges back toward full capacity. 

Perhaps when the pair return to the starting line-up - in all likelihood in Round Four of the FA Cup - there will be an even greater grasp of the extent of a depleted Liverpool's achievement. 

And if the worst is over on the injury front, the outlook is bleak for the Reds' rivals, both domestic and continental.

For there is an increasing possibility (one which Klopp wouldn't dare let his players contemplate) that with Liverpool in complete command of the Premier League, they can mount a fully-fledged European assault as they cruise toward the finish line on home soil.