Saturday night Victor Ortiz will learn just how vicious he is.

It has been six months since he learned he was less vicious than he thought. Or at least less willing to stand up to the viciousness of another fighter more inclined to walk through fire than he was. Six months can seem a long time in a young man’s life but is it long enough to erase the memory of what he did that night at the Staples Center in Los Angeles?

We cannot know. Not even Ortiz can know. Not until he feels the walls crashing in around him again. Feels the hot breath of an opponent whose only goal is to separate him from his senses at any cost. Feels the panic of being unable to respond to the challenge in front of him.

Only then will we, and more importantly he, know whether he is still the brightest prospect in the stable of Golden Boy Promotions or just another kid for whom boxing was not the way out it once appeared to be.

Last June, Ortiz entered the ring as a 22-year-old prodigy, a boxer with a bright smile, a nightmare life story that boxing was turning into a fairy tale and an opponent in front of him he felt sure to remove without too much trouble.

Even after Marcos Maidana (25-1) dropped him in the first round Ortiz was more chagrined than bothered. Soon he had Maidana on the deck. Then he had him down twice more and the fight was only in its second round. Clearly it would not be much longer before Ortiz’s hand was raised for the 25th time and he held his first world title belt in his arms.

And then Maidana said “No!’’ He said, “Let’s fight some more and see, hijo. Let’s see what you are made of.’’

Soon Ortiz' right eye was cut. Then his left eye began to swell grotesquely. Then Ortiz went down a second time in the sixth round and Maidana moved in. It was clear to both men at this point how this would end. The only question left was how the end would come.

And then Ortiz decided. It would end without any more violence. It would end as he turned his back to referee Raul Caiz, Sr., pointing to his fast-closing left eye. He had surrendered.

In an effort to save face for the beaten young prospect, Caiz called in the ringside physician and made a display of stopping the fight but Ortiz had beaten him to it and the boxing world knew it. What made it worse was what Ortiz said after the fight.

“I’m not going out on my back,’’ Ortiz told a dumbfounded HBO audience. “I’m young but I don’t think I deserve to be beat up like this. I have a lot of thinking to do.’’

It was the rawest of emotions – fear, defeat, resignation. It was a young man honestly grasping the harshness of the life he had chosen and realizing he was not sure if it was for him.

Ortiz’s childhood, such as it was, had been a nightmare of a mother who never loved him and walked out on him and a father who took that out on his kids until he, too, was gone. It was a life of homelessness, shame and a fight for survival, a survival that came, really, only because Ortiz was quick with his fists, quick with a smile and gifted in a savage way.

He became a highly touted amateur boxer and the almost instant darling of first promoter Bob Arum and later Oscar De La Hoya and HBO. Life quickly went from difficult to a dream of glory. He was not yet a king but already a prince the night he got in with Maidana and learned there is more to boxing than having your hand raised.

Ortiz was 24-1-1 with 19 KOs the night everything changed. Saturday he will try to reverse the damage against Antonio Diaz, a wily veteran of the fistic trade who has been a title contender and an earnest professional for many years.

Earlier this week Ortiz said at a press conference in Chicago, where he will face Diaz on the undercard of the Juan Diaz-Paulie Malignaggi rematch, that, “What’s done in my past is done. I’m ready to move on.’’

So is boxing but not until Ortiz can erase the memory not of defeat, for defeat comes to nearly everyone who chooses boxing for a living, but rather the memory of the choice he made. The only choice not given to boxers.

Victor Ortiz made the choice to quit in the ring, turning his back to his opponent with one eye cut and the other swollen half shut. It was not an unreasonable choice. In most circumstances it would have been seen as the wise one.

But boxing is not most circumstances. Boxing is desperate circumstances. It is a place where you cannot “tapout’’ as they do without shame in the world of mixed martial arts. In boxing you fight to the end or you are not a fighter. Harsh rules but boxing is a hard place with sharp edges.

Saturday night we will learn a little more about “Vicious’’ Victor Ortiz. We will learn if that night was an aberration, a moment of weakness after a lifetime of steady resolve or if it wa something deeper and more troubling for a fighter.

Ortiz has already overcome many obstacles and if he never fought again, if he simply stuck to his guns and decided he’d already been beaten up enough for two lifetimes between his family and the sport he chose, no one would blame him.

But he has made another choice. Whether willingly or not he has come back to boxing to face his most humiliating moment. How he handles it and the pressure Diaz is sure to try and put on him will say much about who he is.

At this juncture, before the first bell has tolled for him, we cannot say we honestly know. Was last June just a bad night, just a moment of weakness amidst a life of courage? Or was it a peek into the soul of a frightened kid who realized as Maidana beat on him with a heartless resolve that he’d had enough of that kind of abuse?

We won’t know until he and Diaz square off and maybe not even then. Not until he finds himself once again feeling trapped and put upon. Only then will we truly learn who Victor Ortiz really is. That is why we will watch and why he will fight again – because we want to know the answer and so does he.