The intense focus that has centered around one elite Liverpool great turned to another on Anfield's latest frustrating night.
Mohamed Salah has been under scrutiny for his struggles this campaign - and was placed on the substitutes' bench for the second straight Premier League game as the Black Cats arrived on Wednesday.
But it was leader Virgil van Dijk, a unmatched defensive foundation as Liverpool have secured the array of major prizes, whose struggles came under the microscope during the stalemate.
Van Dijk, 34, and Salah, 33, both inked new lucrative two-year deals in the summer, with scarcely a Liverpool concern voiced at the notion of offering extensions to a veteran duo much nearer to the end of their careers than the start.
In fact, it was a moment of optimism - but now there is no avoiding the harsh truth that standards have dropped alarmingly for both.
Liverpool have been susceptible in defence ever since boss Arne Slot and the club's scouting department undertook a £450m summer rebuild that has yet to prove anything like a good return.
Concurrently, Van Dijk has started to lose the air of invincibility he has carried since his £75m transfer from Southampton in January 2018.
Van Dijk has faced additional challenges by fellow defender Ibrahima Konate's dramatic dip, along with Milos Kerkez not finding his feet at left-back. But the esteemed defender has also fought his own battles, as demonstrated by his rash handball that gave away a penalty in the heavy Champions League loss to PSV Eindhoven at Anfield.
It was exemplified in the 67th minute on Wednesday when Chemsdine Talbi gave Sunderland a merited lead, Van Dijk giving the ball away before backing away and turning away on a 25-yard shot that deflected off him and looped out of the reach of goalkeeper Alisson.
For a defender of such unquestionable quality, Van Dijk has an peculiar tendency of turning away on the ball, sometimes to Liverpool's cost.
Misfortune at the conclusion, yes, but it was a situation Van Dijk courted with his unusual failure to act decisively, Sunderland's Talbi capitalising.
"Van Dijk surrenders possession and then he just retreats. It's the wrong decision. He needs to go to the ball. Him not making the decision means that no one else knows what to do."
"Virgil Van Dijk last season couldn't make a mistake. Every game he was imperious, but right now he's making mistakes and doubting himself."
As with Salah, a player of Van Dijk's pedigree must not be dismissed after winning two Premier Leagues, the Champions League, the FA Cup and two EFL Cups in a stellar Liverpool career.
He has, though, looked a faded version of his usual imperious self this season, with the poest ball recovery rate per game during his Liverpool career, while key defensive stats are also down on last season.
And, while leadership should not be Van Dijk's exclusive domain alone in a Liverpool team packed with experience, it was absent here. No-one was rousing a team that once again looked bewildered to seize the initiative by the scruff of the neck.
Van Dijk's subpar showing, which ended with him being used as the last resort of acting as an makeshift forward, was symptomatic of a horribly mediocre Liverpool performance - which made Sunday's win at West Ham seem like the exception rather than the rule.
Slot stayed with the side that ended a run of nine losses in 12 games at London Stadium, Salah once more watching from the sidelines.
The Egyptian came on at the start of the second half as the Kop looked to him for inspiration. It was not forthcoming, with £125m Alexander Isak also anonymous after getting off the mark with his first league goal for Liverpool on Sunday.
Slot would have been under greater pressure had Florian Wirtz's 81st-minute shot not deflected in off Nordi Mukiele to set up what Liverpool hoped would be a thrilling finale.
A late scare came - but at the other end. Liverpool were only avoided defeat in stoppage time when Federico Chiesa's excellent defensive sprint allowed him to turn Sunderland substitute Wilson Isidor's shot off the line after he had dribbled past keeper Alisson.
Slot and his fading champions ultimately had to accept the point knowing it could have been worse, with Alisson blessed to turn Trai Hume's shot onto the bar in the first half before Omar Alderete headed against the post after the interval.
Liverpool were sluggish, unimaginative and lacking in ideas. Even the traditional late rally after the equaliser carried little conviction. Displays like this are the reason their attempt to retain the title has crumbled.
But huge credit for the Reds' struggles on Wednesday must be given to Sunderland, who are being seeing the results for a summer of notable ambition in the transfer market, coupled with the excellent coaching of Regis le Bris.
The Black Cats were positive, confident and threatening.
Sunderland are now sixth in the Premier League with 23 points. It is symptomatic of the manner in which they have grown into life in the Premier League that they will be frustrated they left Anfield without adding two more to their tally.
For Slot and Liverpool, it is back to the drawing board.
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Allison Bartlett
Allison Bartlett
Allison Bartlett
Allison Bartlett
Allison Bartlett
Allison Bartlett