Defending the name of the game for Klopp as his reputation and Liverpool's hesitant backline are put on trial
What's gone wrong with Jurgen Klopp? Or, to put it another way, is it something that, among all the brilliance and passion, was never right from the start? Does he really grasp how to organise a defence?
We will know a little better at Anfield today when, ironically enough, his chief interrogator will be one of his dearest friends, Huddersfield Town manager David Wagner. Wagner, who worked under Klopp as reserve team coach at Borussia Dortmund, last weekend ambushed Jose Mourinho's Manchester United.
Today his task is to prosecute, and, yes, discredit one of the starkest challenges ever presented to a leading manager.
Klopp, dismayed by the brittleness of his team against Tottenham, quite as much as a growing army of critics, has sworn to put things right.
It is not often that a man of his football stature is required to make such an undertaking but then how could he avoid it?
The Liverpool manager dragged off the hapless Dejan Lovren after just 31 minutes. He said that Lovren's partner in central defence, Joel Matip, was equally at sea and claimed that he could have done better out there himself, wearing trainers.
This wasn't condemnation. It was a soul-bearing, virtually unprecedented in the history of big-time football management.
Today he has to show that he has put it right. One small comfort in the crisis is the support of Graeme Souness, one of the most formidable figures in the history of the club.
Souness didn't play football to make people happy, which is Klopp's driving incentive and also, incidentally, the proclamation attached to his great predecessor Bill Shankly's bronze statue behind The Kop.
The fiery Souness played to win, with skill but also with great hardness and practicality.
And he still believes that Klopp, despite Liverpool's ninth place and just one win in six games, is the "right fit" for Anfield, that he speaks the language of his people and has the capacity to create the level of emotion which, sooner or later, will produce success. This is always assuming, of course, that the defence is something more than a collective green traffic light.
The challenge for Klopp is to bring in some order and defiance before the distant January window, and maybe a renewed attempt to sign the polished Southampton defender Virgil van Dijk, or at least someone approaching that quality.
It comes down, literally, to a holding operation as Liverpool attempt stay in touch with the possibility of a top four place.
And it is one plainly that Klopp must pull off, starting today when so many are asking how it is that one of the most charismatic figures in football is suddenly fighting for his job. One suggestion, by Eamon Dunphy, is that there are times when Klopp appears to be nothing so much as the product of charm.
Yet mere charm doesn't win back-to-back Bundesliga titles under the weight of Bayern Munich - or go within an inch of beating them in a Champions League final. Or propel his first and modest club, Mainz, into the top German league for the first time in their history.
Klopp, no doubt, is something of an enigma. His mood swings from benevolence to hard anger and wrenching sarcasm.
But there is, no doubt, at the heart of him something which is irresistible and which, so far, has headed off the worst signs of unrest on the Anfield terraces.
Mostly, if we can draw a veil over the angst that came following the Wembley debacle, is a superb capacity to identify with the hopes and the hurts of his players.
Certainly as the pressure mounts on Klopp at Anfield, there is no shortage of evidence that he is a man who has touched deeply so many of the players who have matured under his leadership.
Not the least supporting witness is the great Polish marksman Robert Lewandowski.
"He is the one who made me believe in myself," says Lewandowski. "In my first days after coming from Poland he would play one-on-one games with me at training sessions. We would have bets on whether I would score.
"Eventually, I finished up with a positive balance, but he taught me a lot before that. He won the first games and was happy but then he was not so keen to bet.
"It was with him that I saw for the first time how important it was to train. I saw what I had do on the pitch when I didn't have the ball, what positions I had to take and when I see Liverpool attacking now I see his work. He was always showing me the way to improve and I think he will do that at Liverpool."
Maybe, if he is granted the time - and is able to bring in a little defensive support for outstanding attacking potential.
Certainly there will be no absence of feeling, no cold application of theory.
His fondness for players who have passed his test of football values is clearly huge.
When Shinji Kagawa, who came to Klopp's Dortmund from the Japanese league, struggled at Manchester United, his former coach was said to have wept with frustration.
"Why is such a good player not used properly?" Klopp asked. "It is a terrible waste."
Kagawa says: "Jurgen Klopp will change Liverpool. He is a great coach and in the end his results will prove it.
"Every moment I had with him is a good memory. He treated me so well, taught so much, even though I was from Japan and not at all famous."
Such testimonials will not mean so much if the Liverpool defence fails to work today.
The suspicion is that Klopp will thrust the impressive young Joe Gomez into the centre and jettison goalkeeper Simon Mignolet in favour of Loris Karius.
This, though, is a question of personnel. The bigger one is whether Jurgen Klopp can prove, at one of the most critical points of his career, that he has more than charm and panache.
Indeed, that he is familiar with the essential business of defending his goal, and, perhaps, his job.