The Teacher is not teaching. At least that’s what Nacho Beristain wants you to believe.

The 69-year-old Beristain is one of the greatest trainers ever to come out of Mexico’s fight factories, a well-respected scholar of pugilism even in his younger days when he did not have the kind of talented fighters he handled in later years. For the moment, he is directing the fortunes of Oscar De La Hoya, preparing him for what arguably is the biggest fight of the Golden Boy’s career, because if he loses to Manny Pacquiao he will be 0-6 in such transcendent moments, and left with a difficult argument to make for himself when the debate begins over his place in boxing history.

Beristain is oblivious to that, however. His concerns are more technical and more focused on what needs to be done to counteract Pacquiao’s southpaw stance and speedy hands. To do that may require certain alterations in how De La Hoya approaches his business, yet Beristain, one of the world’s great teachers, insists that is not what he is about now.

“There’s nothing for me to teach Oscar,’’ Beristain insisted this week. “Oscar is a complete fighter already. My job is to just maybe correct some little details that Oscar needs to work on, such as his body movement, or maybe his shoulders and how they have to move with his body.’’

Beristain has prepared some of Mexico’s greatest champions for battle, guys like Ricardo “Finito’’ Lopez, Daniel Zaragoza, Humberto “Chiquita’’ Gonzales and most recently Rafael and Juan Manuel Marquez. The latter may be the fighter of most interest today because he has twice fought Pacquiao, once to a draw and the second time to a hotly disputed split decision defeat that Marquez and Beristain still look upon with contempt.

De La Hoya has admitted it was Beristain’s knowledge of Pacquiao that was part of the attraction when he hired him to be the seventh trainer of his career and his third in as many fights, calling him his “strategist’’ more than his trainer.

To have such a constant din in a fighter’s ear might be daunting to some guys and difficult for the new trainer to cope with because he could well feel he is constantly undoing somebody else’s work but Beristain doesn’t worry about what Freddie Roach or Floyd Mayweather, Jr. were saying to De La Hoya when they had him in the gym.

Rather, he is up in Big Bear, California, high above the smog of Los Angeles, preparing his newest acolyte for the harshest of tests – the kind that come inside a 20-foot boxing ring – in the way he always has – with obsession and an iron hand.

But is he teaching him anything new? Well, that depends on who and what you want to believe.

One moment Beristain is insisting he is only polishing a diamond, not reshaping a stone. In the next, he’s asked about the decision to bring in 87-year-old Hall of Fame trainer Angelo Dundee as an advisor. Does De La Hoya need more advice or does Beristain?

“I’m happy because Angelo Dundee is a legend,’’ Beristain says politically. “He’s going to be helping in some technique aspects, maybe some advice or just exchanging points of view.

“The only thing I can tell you is he’s going to be there during the fight, yes, but I am the one that is going to lead the corner.’’

And when he does lead, how will he exploit the obvious physical advantages De La Hoya holds? With a six-inch edge in reach and clearly the more naturally bigger guy, one would assume Beristain will take those factors into account and convert them into a plan of attack that will maximize their virtues while minimizing the ones Pacquiao holds.

Talk about this with The Great Teacher however and suddenly the advantages disappear and all that’s left are two guys in the ring. Or so Beristain wants you to think.

“I think there are no advantages for Oscar and there are no advantages for Manny Pacquiao,’’ Beristain said. “I think it’s going to be a very even fight. And I can tell you it’s going to be a very interesting fight.

“Oscar is the type of fighter who can adjust himself to different opponents or different fighting styles. Come December 6, I think you’re going to see an Oscar De La Hoya that is going to be ready to fight a southpaw.

“Manny Pacquiao’s style is very awkward, very different, but Oscar De La Hoya is the type of fighter that can adjust himself.’’

Part of that adjustment has been working with Beristain, who is known as a demanding and strict trainer. Rival promoter Bob Arum has called him “a control freak’’ and has speculated Beristain will try to radically alter De La Hoya’s style, which will be a disaster because the fighter is “not a quick learner.’’

Beristain counters such talk by insisting he’s not changing anything, just finding ways to accentuate the positive, eliminate the negative and not mess with Mr. In-Between.

The truth, as is often the case in life, lies somewhere in the middle. Certainly a trainer who has created a nearly perfect boxing technician like Juan Manuel Marquez will see things he does not like in De La Hoya and try to fix them. But he is also smart enough to understand that wholesale changes of a 35-year-old, six-time world champion are counter productive and foolish at this stage of his career.

So what is he really doing up there in Big Bear every afternoon with De La Hoya? Nacho Beristain isn’t really saying, but Golden Boy Promotions CEO Richard Shcaefer insisted something is going on.

“I talk to Oscar when he’s in camp usually twice a week and I really have never heard Oscar as excited as he is to be able to work with the legendary trainer Nacho Beristain,’’ Schafer said.

“It’s sort of like when you go to school and you want to learn, you want to continue to learn. You don’t stay with your first grade teacher throughout your entire career. You want to be able to continue to learn and Oscar is fortunate enough to have been able to work with some of the greatest trainers of this generation.

“He tells me that he always felt Mayweather, Sr. was the best trainer. I know that Mayweather, Sr. is always out there telling everybody that he is and Oscar actually felt he was but just the other day Oscar was telling me that out of all the trainers he’s worked with, he truly feels Nacho Beristain is the best.

“He called him the teacher. The professor. He said, ‘It’s amazing at this point in my career what Nacho Beristain is teaching me.’ He’s like a young student. Oscar is willing and able to soak in all the great information and techniques Nacho Beristain is teaching him.’’

So is he or isn’t he? In the end, what does it matter? What really matters is that when a magazine writer recently asked Beristain if De La Hoya was likely to have difficulties with Pacquiao his answer summed up his outlook on it all in one word.

“No,’’ Beristain told Vanity Fair. Then he lit a cigar.

The message was clear. Whether Nacho Beristain is trying to remake Oscar De La Hoya or simply creating a roadmap for him, he believes he’s going to beat Manny Pacquiao. How he does it – teaching, strategizing, motivating – is far less important than that he do with Oscar De La Hoya what he could not with Juan Manuel Marquez.

“All I can tell you is we’re working in a very peaceful and harmonious way because working with De La Hoya, Joe Chavez, Rob Garcia and myself makes everything run smoothly,’’ Beristain said. “So I think Oscar is going to be very ready for this fight.’’

So will The Teacher, whether he’s lecturing on technique or creating a battle plan.