Leeds United boss head coach Marcelo Bielsa has had a huge influence on many players and coaches in the football world - none more so than Manchester City chief Pep Guardiola.
When Guardiola was at the start of his coaching career, he went to see Bielsa for advice and guidance.
The Spaniard has revealed how the pair talked for 11 hours - and it had a lasting impact on him.
Guardiola has coached Barcelona, Bayern Munich and now City, winning a glittering array of silverware along the way.
Bielsa has taken a slightly different path, from Newell's Old Boys, Atlas, America, Velez Sarsfield, Espanyol, Argentina, Chile, Athletic Bilbao, Marseille, Lazio and Lille to Leeds.
Now the pair are Premier League rivals, after the Argentine led the Whites to promotion from the Championship last season.
Guardiola revealed an insightful snippet from their epic chat in an interview with DAZN, which has now been translated from Spanish and subtitled by self-confessed Bielsa "apostle" Juani Jimena.
"The truth is that, yes, we were talking for 11 hours," said Guardiola.
"I will never be able to thank Marcelo for how he has treated me, because I was nobody at that time.
"I had just got my coaching licence - and he received me. And when you are nobody, that a coach receives you like this and how he treated me, it was wonderful - like Cesar Luis Menotti (former Argentina head coach) the day before."
Bielsa had apparently warned Guardiola about the various pitfalls of becoming a coach, including the media spotlight.
Guardiola added: "Bielsa spoke to me about the media and then I was the one who asked him, if we complain so much about this world of football, that it won't let us live, then I asked him: 'Marcelo, why don't you train in an academy? A more amateur world, and you forget about this professional world, the media, the criticism, high-level players'.
"And it was he who answered me: 'I need this blood. I need this.'"
This striking symbolism gives a rare insight into what drives the 65-year-old after all this time. It may be painful at times - but he would not have it any other way.
Leeds and Manchester City played out an entertaining 1-1 draw at Elland Road earlier this season.
Bielsa and Guardiola are set to go head-to-head once more for the return fixture at the Etihad Stadium on Saturday, April 10.
