Liverpool’s famous front three have taken them to the brink of a first top-flight league title in 29 years, but scratch beneath the surface, after missing an opportunity against injury-ravaged Manchester United, and Liverpool’s lack of alternatives could see their agony prolonged for one more season.

When Philippe Coutinho departed for Barcelona for an astronomical amount of money last January, Liverpool’s “Fab Four” was no more, and it was feared their famed attacking force would be blunted without their creative figurehead.

Instead, Sadio Mane, Roberto Firmino and especially Mohamed Salah became an even greater attacking triumvirate, with defences across the continent unable to contain them as they plundered a colossal 30 goals in the Champions League last season – 10 strikes each.

Sane, Firmino and Salah carried their goalscoring threat through to the turn of the year, as Liverpool close in on a first-ever Premier League crown, but, for the first time, not one of the famed trio is in good form as we approach the business end of the season, and, more worryingly for Liverpool fans, after another ineffectual showing at United, the alternatives do anything but get the pulses racing.

“Liverpool's front three haven't quite exploded this season and they're going to need them to if they're going to win the league,” Jamie Carragher said after draw at Old Trafford. “Liverpool's first XI is top class but what is coming from the bench probably isn't enough.”

Taking Liverpool’s 4-3 victory over Crystal Palace in mid-January as an outlier, Salah, Mane and Salah have five goals and one assist between them in 2019, in all competitions. Not catastrophic form by any means, but by the high standards the trio have set themselves, when fighting for a league title, that is far from an impressive run.

In that time, Sergio Aguero alone has 11 goals and one assist to his name. Then you have Raheem Sterling, Leroy Sane, Gabriel Jesus etc. This is Liverpool’s problem: this is no ordinary title race, they are competing against an almost unstoppable force.

To win the title, Liverpool will likely have to breach the 90-point mark, something only achieved six times in Premier League history, but this is what City, who are starting to find their relentless top gear at the right time, have done – they have raised the standard, and to beat them, you are going to have to be near-perfect.

That means Liverpool really needed to win a game against a United side who were forced to use all their substitutes in the first half, and had Marcus Rashford limping up front for the majority of the second half, with Romelu Lukaku on the right wing.

A draw at Old Trafford, a ground where Liverpool have not won for five years, is by no means a bad result, and may well prove to be a point that ends up being decisive, but this is no ordinary title race, against no ordinary challenger.

"On days when United are beatable you have to do it," Jurgen Klopp said after the match. "It is a point at United and everybody feels it could have been more.”

Having started the match in great voice, with a new-look United now capable of going toe-to-toe with Liverpool, Old Trafford looked resigned to their fate in the second half, but Liverpool could not deliver the fatal blow.

In a game of such fine margins, where one moment of brilliance can decide the match, substitutes can have a huge role to play. United manager Ole Gunnar Solskjaer proved time and again the value of quality from the bench in his playing days.

Liverpool, though, look painfully short of cavalry options. Daniel Sturridge, after years of injury hell, is a shadow of the player he was, and offers next to no attacking threat.

There was one amusing moment in the second half when Sturridge, Firmino’s replacement, went running over to the bench, as it appeared the substitute was being substituted. Not a soul in the stadium looked surprised.

He was, in fact, taking instructions from Klopp, but even that failed to inspire him. The next option was Divock Origi, who aside from his fluke goal in the Merseyside derby in December, has not scored a Liverpool league goal since May 2017.

Xherdan Shaqiri looked like a really astute signing earlier in the season, proving a real effective weapon from the bench. However, his form has completely tailed off.

In his last six league appearances for Liverpool, Shaqiri has created just one chance, and not registered a single shot on target – the very definition of ineffective.

And that is about it, there simply is nobody else. For City, if Aguero has an off day, on comes 16-goal Gabriel Jesus. If Sterling misfires, on comes Sane. If Bernardo Silva cannot create chances, on comes Mahrez. You get the picture.

It has come at a great cost, but City’s squad, not just first XI, is one capable of winning titles. Liverpool’s is close, their first XI is excellent, but scratch beneath the surface, and there is not much else there.

Any other season and they could well have enough to end that long wait for a Premier League crown, but this is no ordinary season.