Quite apart from his defensive qualities, Liverpool could really do with Virgil van Dijk's leadership right now. 

Going into the weekend's fixtures, the champions were seven points adrift of Manchester City, with Pep Guardiola's side also boasting a game in hand. 

As much as the burden of responsibility has fallen on the Reds' misfiring attackers, Van Dijk's injury will probably go down in history as the major sliding doors moment of their season. 

That collision with Jordan Pickford in the Merseyside derby - for which the Everton goalkeeper wasn't punished - has had serious ramifications for Liverpool's title defence. 

Of course, the crisis has also been exacerbated by subsequent injuries to Joe Gomez and Joel Matip, though neither of those will be remembered as quite such a significant 'what if?' 

With Andy Robertson conceding that Liverpool are "not in the title race" after the 1-0 defeat to Brighton at Anfield, some eyes are already turning towards next season. 

The question isn't just when Van Dijk will be back, but what level he'll be at when he completes his rehabilitation from a notoriously complex, painful and debilitating injury. 

Will Van Dijk be the same player? 

Now the history books are divided on the subject. Roy Keane, Alan Shearer and Xavi all bounced back from ACL tears and continued to excel. On the other hand, there are the sad cases of Michael Owen and Radamel Falcao, players who never again reached their pre-injury levels. 

Age could be a key factor. Medical knowledge of ACL injuries has advanced, but it's worth remembering that Van Dijk could be 30 by the time he next pulls on a Liverpool shirt. 

Yet perhaps one of the best indicators of how the Dutchman will bounce back comes from Dr. Rajpal Brar. 

Having studied footage of the centre-back's rehab programme, he has provided a number of key takeaways. 

The full video can be seen below: 

One clip shows Van Dijk controlling the ball as it drops from height. It might look like a run-of-the-mill training exercise, but Dr. Brar highlights what it tells us about the defender's recovery. 

"The ball drops to the right and he moves that way spontaneously, which hints at good movement confidence," he said.

"Overcoming that mental aspect when returning from ACL rehab is something we know is critical for returning to pre-injury levels and one of the last things to come back.

"So that ability bodes well for VVD. Although it is quite early in that regard."

What does Van Dijk's rehab include? 

There were other positive signs, including the former Southampton man working on his strength via loaded step-ups in the gym, hamstring slides, loaded squads and blood-flow restriction training (BFR). 

The latter allows athletes to perform low intensity training but replicate the same blood flow levels as in high intensity workouts. 

It's also pointed out that while Van Dijk's speed of recovery has been impressive - the only injury only happened in October - we shouldn't read too much into that. In fact, it's to be expected from an elite athlete with one of the best medical teams in the world working with him.

At some point later this year will come the real test when he finally returns to Premier League action.