The glaring attention that has been trained on one world-class Liverpool icon turned to another on Anfield's latest disappointing night.
Mohamed Salah has faced examination for his subpar performances this season - and was placed on the bench for the second successive Premier League game as the Black Cats visited on Wednesday.
But it was skipper Virgil van Dijk, a unmatched defensive rock as Liverpool have collected the complete set of major prizes, whose poor form 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 prospect of offering extensions to a seasoned pair 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 stark fact that levels have fallen worryingly for both.
Liverpool have been exposed in defence ever since manager Arne Slot and the club's transfer committee began a £450m summer refit that has still to demonstrate anything like value for money.
Concurrently, Van Dijk has started to forfeit the air of invincibility he has possessed since his £75m switch from Southampton in January 2018.
Van Dijk has received little support by fellow defender Ibrahima Konate's dramatic dip, along with Milos Kerkez not finding his feet at left-back. But the great Dutchman has also had significant difficulties, as demonstrated by his panic-stricken handball that gave away a penalty in the heavyweight Champions League loss to PSV Eindhoven at Anfield.
It was exemplified in the 67th minute on Wednesday when Chemsdine Talbi gave Sunderland a deserved lead, Van Dijk losing possession before retreating and turning his back on a 25-yard shot that hit him and looped out of the reach of goalkeeper Alisson.
For a defender of such unquestionable quality, Van Dijk has an curious trait of turning away on the ball, sometimes to Liverpool's cost.
Misfortune at the conclusion, yes, but it was a situation Van Dijk invited with his unusual failure to make a decisive move, Sunderland's Talbi capitalising.
"Van Dijk loses the ball and then he just backs off. 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 dominant, but right now he's erring and doubting himself."
As with Salah, a player of Van Dijk's caliber must not be dismissed after winning two Premier Leagues, the Champions League, the FA Cup and two EFL Cups in a glittering Liverpool career.
He has, though, looked a faded version of his usual dominant persona this season, with the worst recoveries per game during his Liverpool career, while tackles and interceptions are also down on last season.
And, while leadership should not be Van Dijk's exclusive domain alone in a Liverpool team brimming with experience, it was missing here. No-one was motivating a team that once again looked clueless to take control by the scruff of the neck.
Van Dijk's difficult night, which ended with him being used as the emergency option of acting as an last-ditch attacker, was representative of a horribly mediocre Liverpool performance - which made Sunday's win at West Ham seem like the anomaly rather than the norm.
Slot persisted with the side that stopped a run of nine losses in 12 games at London Stadium, Salah once more starting on the sidelines.
The Egyptian was introduced at the start of the second half as the Kop looked to him for inspiration. It was not forthcoming, with £125m Alexander Isak also quiet after scoring his first with his first league goal for Liverpool on Sunday.
Slot would have been under increased scrutiny had Florian Wirtz's 81st-minute shot not deflected in off Nordi Mukiele to set up what Liverpool hoped would be a thrilling finale.
Late drama came - but at the other end. Liverpool were only avoided defeat in stoppage time when Federico Chiesa's superb tracking back allowed him to turn Sunderland substitute Wilson Isidor's shot off the line after he had rounded keeper Alisson.
Slot and his fading champions ultimately had to settle for a draw knowing it could have been worse, with Alisson fortunate 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, ponderous and short on invention. Even the customary late surge after the equaliser carried scant belief. Showings like this are the reason their title defence has fallen apart.
But huge credit for the Reds' struggles on Wednesday must be given to Sunderland, who are being seeing the results for a summer of serious ambition in the transfer market, coupled with the fine work 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 unhappy they left Anfield without adding two more to their tally.
For Slot and Liverpool, it is time for reflection.
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