For Marseille, things couldn’t be going much better at the moment. The team stands seven points clear at the top of Ligue 1, having won its last eight games in a row. It’s scored 25 goals in 10 games, five more than the next highest scorers. It’s playing brilliant, dynamic, viscerally thrilling soccer. If it can cling on and see off the financial might of Paris Saint-Germain to win le Championnat, it would be one of the great fairy-stories.

The sense of romance is enhanced by the identity of the man responsible. Marcelo Bielsa led Argentina to Olympic gold in 2004 but, other than that, he has won nothing since lifting the Argentine Clausura with Velez Sarsfield in 1998. In the 16 years since, Bielsa has become the sport’s fundamentalist, devoutly pursuing his ideal of football even while acknowledging that doing so may be costing him trophies. “If players weren’t human, I’d never lose,” he commented in his time at Velez, a moment of self-awareness he has ignored ever since.

His followers – and there are many, including Pep Guardiola, Mauricio Pochettino and Jorge Sampaoli – have tempered his approach, acknowledging here must be a compromise between the ideal and what is possible, and have been far more successful as a result. Bielsa, really, is a better theorist than he is practical coach. And yet he goes on, chasing always after the dream. Perhaps there is something vainglorious about his approach, but there is also something remarkably pure about prioritizing the process over the outcome. And, of course, if he did topple PSG, the achievement, after all the years of failure, would be so much the greater, the apotheosis of bielsisme conquering, however briefly, modern football’s wearying economic imperative.

If it happens, that is – if Marseille can cling on. And that’s the real problem with bielsisme.

The template is clear with Bielsa’s club sides. There is an uncertain start, as players begin to adapt to his method. Then there comes the period of victories and excitement, the upswing of fine form. “At first he seems tough and he may even annoy you with his persistence and don’t-take-no-for-an-answer resilience, but in the end he is a genius,” said Fernando Llorente, who played for him at Athletic of Bilbao. Others have spoken of a sense of profound revelation, of Bielsa awakening in them a remarkable understanding of the inner workings of the game.

Bielsa’s basic theory is actually relatively simple. He watches videos of future opponents obsessively – and has apparently developed the capacity to watch and absorb two screens at once. He discerns shapes. He sees the unconscious patterns in how other sides build up the play. He works out how to obstruct those rhythms, where possession may most simply and most dangerously be regained, then imparts that knowledge to his teams. The ideal Bielsa game will feature most of his players in the opposition half most of the time. That’s why he often uses a back three: to get as many players as possible, as high up the pitch as possible, so the pressing can be as focused and as potent as possible. It’s also why so many former Bielsa players, trained to think in terms of those shapes, go on to become coaches.

The problem is that pressing in that way is exhausting. It requires constant physical effort. There can be no slacking: efficient pressing is a team activity, and one weak link can destroy the whole process. It’s also mentally draining. Thinking constantly about patterns and shapes, which change form game to game, wears players down. After the period of good form, which tends to last around six months comes collapse. Players simply cannot keep going, shattered in body and mind.

At Athletic, Bielsa reached the heights as his side beat Manchester United in each of the two legs of the Europa League last 16 tie with a pair of brilliant, memorable performances. By the time Athletic reached he final, though, fatigue had set in and it was well-beaten by Atletico. It was the same story in the Copa del Rey: invigorating progress to the final followed by collapse and a limp performance in defeat to Barcelona.

Once weariness sets in, there is no way back. Bielsa has no other way, and that’s when the recriminations begin. Players who had led him as a genius begin to describe him as unreasonable. The fights picked with management that seem part of a quirky irascibility when results are good, become intolerable when result are bad. Already Bielsa has been openly condemnatory of the Marseille board; that will bite him if the results dry up.

Sunday’s match away to Lyon represents Marseille’s biggest test of this season so far, but the real challenge will come in March. Can Marseille keep going? Will fatigue set in again? Will it be far enough ahead to stagger over the line? Can this be Bielsa’s great consecration, or will the paradigm repeat again?