Marco Antonio Barrera understands the scenario that has been laid out for him. He is walking a path trod by so many great champions before him when gray flecks begin to appear in their hair. He has been brought to the arena to lose.

Saturday afternoon (4 pm US time) Barrera will be at the MEN Arena in Manchester, England for the purpose of improving someone else’s resume. If that were not the belief of those who arranged this fight with young Amir Khan, the bright British prospect with the limestone chin, he would not be here. This Barrera understands completely, which is not the same as accepting its validity.

Frank Warren is many things, but not a risk taker. England’s finest and most successful promoter, Warren has often been criticized for not putting his best fighters in against top competition if there is any way to avoid it, which is why the general consensus is that Warren must believe Barrera is well shot.

Otherwise, why would he put Khan, a British boxing hero without having yet won a single championship even at the Olympic level, in the ring with a man who has won world titles in three weight classes and will one day be inducted into the Boxing Hall of Fame?

Warren is convinced he has put Khan in the perfect position. He is facing a revered former champion from whom Khan will get the keys to bigger paydays without having risked the dangers Barrera would have once represented. He is, in essence, fighting an imposter – a Marco Antonio Barrera but not the Marco Antonio Barrera.

Barrera has heard all this talk. He has heard experts claim his skills have diminished beyond repair. At 35 and the loser in his last two big fights to Manny Pacquiao and Juan Manuel Marquez in lopsided fashion, Barrera is a realist. He does not deny he is not what he once was. His point is different.

His point is that what he still is will be good enough. Good enough to teach this young man why boxing is called the hurt business.

“He has never faced a fighter with my level of skills,’’ Barrera said recently. “I know about his hand speed. I know about his footwork. I know about his chin, too.’’

With that a man once known as “The Baby-Faced Assassin’’ smiled the smile of someone who hurts people for a living. It was a smile without humor. The kind of smile nearly all of Barrera’s opponents got to see when it was too late, including Khan’s idol, the former champion Nazeem Hamed.

Hamed was a hot property the night he faced Barrera, who even then was rumored to be on the downside. By the time he was finished with Hamed it was Hamed who was on the down side, beaten to the point that he never fought again.

Khan has promised to avenge that defeat Saturday night. Barrera has reminded him of the savage beating his friend took for making the same mistake Khan now has. It is a memory he wants Khan to keep fresh in his mind as the final hours tick down and night falls on Manchester, a memory that will accompany him into the ring, a place where the door only opens in, not out.

“I’m not coming there to be a step (stepping stone),’’ Barrera snapped. “I’m coming to win. They were worried about my cut (in an ill-advised tune-up fight in Mexico in January). Amir Khan should not be worrying about no cut. He should be worrying about the fact that I’m coming for him. He’ll get 100 percent of Marco Antonio Barrera on March 14.’’

The question is how much of Barrera is left? Is 100 per cent of this version enough to defeat youth, speed and hunger even if Khan does seem to have a serious chin deficiency?

Barrera believes so, even though in a light-hearted moment he hinted that he understands the Barrera who will arrive in Manchester is not quite the same one that battered Hamed into retirement eight years ago at a time when Khan was a young amateur who adored Hamed and hated Barrera for what he did that night.

“When I was 17 I went to fight at the Forum in Los Angeles,’’ Barrera recalled, “and because I was so young and powerful they called me ‘The Baby Faced Assassin.’ I think that name is no good any more. But what does that matter? I’m winning this fight. You can bet on that.

“When I was young I studied to become a lawyer. I went five semesters (to college in Mexico) but I had to dedicate myself to the sport of boxing. That is what I naturally loved. I think I really did make the right decision.

“Now there are people out there who say I’m not a contender any more and I want to make clear that I am. I know who I am. If they don’t know who I am I will show them on March 14.’’

If Barrera can defeat Khan and then win the lightweight title in his next fight he would become the first Mexican fighter to win world championships in four weight classes. He would have done something his long-time rival Erik Morales never did. He would have done something not even the great Chavez, who is his idol and that of every Mexican boxer, accomplished.

He would make history. To do that, he knows, he first must make Amir Khan realize there are opponents and then there are men like Barrera.

Barely two months after signing him, promoter Don King took Barrera to China and somehow off a win against journeyman Sammy Ventura, a fourth round stoppage that meant little, Barrera became the WBO’s mandatory challenger for the lightweight championship. That being the case, Barrera (65-6, 43 KO) doesn’t need to fight Khan (19-1, 15 KO) or anyone else to get what he says he wants. Yet he is in Manchester anyway, because he is a professional and thus is being well paid to give Khan the chance to make a name for himself at his expense.

But he is there for quite another reason too. He is there to win regardless of what Frank Warren or Amir Khan may think.

“I know I can retire and be a legend right now but I am only 35,’’ Barrera said. “I still have a lot to give to boxing. Retirement will come one day. Two or three more fights. But not yet.

“If I beat this kid, it will get me a shot at the title. That is what is driving me, the chance to be the first Mexican to be a world champion in four divisions. I want to write my name in history in Mexico. I just know the win is coming.”

That has been the mantra that blinded many ex-champions as they began to fade away. They all knew the next win was coming but when the fight arrived most often youth prevailed and only sadness reigned for the fallen former champion.

Barrera knows this because he saw it in the most painful of ways. He saw his idol, Chavez, suffer it at the hands of young Oscar De La Hoya and too many fighters after him. He saw even a journeyman like Frankie Randall beat Chavez, so he understands at some point, skills evaporate. No one knows where they went but they are gone.

Yet he and King believe what Khan and Warren think is impossible. They believe youth will not be served this night. Rather, it will be served up at the altar of what Marco Antonio Barrera once was.

“When a guy like this pops up on your doorstep unexpected it’s SPIRITUAL, man!’’ King thundered. “He called up one of my guys and said he wanted me to promote him. I brought him in and told him how it was and started working with him.

“With guys like this, it’s a mind game. New guys in promoting just look at the physical prowess but if you get into the man’s mind and revitalize it and he’s got championship qualities, you can do great things.

“Barrera is a fighter. He’s got Julio Cesar Chavez qualities. He’s a warrior, man. You get someone like that come to you and he wants to fight, you got to sober his mind first. Plant the seed of invincibility. The physical you can work on but the mindset is what makes the fighter.

“We’re going to come over there to merry olde England and shock and amaze! They’re talking like FDR (U.S. depression-era and WWII president Franklin Delano Roosevelt) who said, ‘We have nothing to fear but fear itself.’ I want them to keep that mindset until the night of the fight. Then it’s too late for them.

“I sat down and talked with Barrera to see if there were any inhibitions. He wanted to fight. He said the people saying he was finished don’t know him. I’m confident Barrera will rise to the occasion. Khan thinks he’s going to catapult himself but I’m betting everything on Barrera because when it comes to a fighting nature he has it hands down over Khan.

“When Khan got in a fight where that had to come out he got himself knocked out. I’m going to get a thrill out of this, bringing back the hero of the Mexican people. Once I felt he was still able to fight I went into what it means to be a Mexican fighter. He stood up strong.’’

He even stood up to his brother, who has long been in his corner. After Barrera sustained a serious cut in a meaningless tune-up fight in Jalisco, Mexico on January 31 in a victory over Freudis Rojas (1-7-1) not far from Barrera’s hometown that King opposed him taking, his brother wanted him to postpone the Khan fight or call it off all together.

He felt there was no need for it with a title shot already secured, arguing that the reward was not worth the risk. King disputed that, pointing out that in boxing nothing is secure, especially the head that wears the crown, or used to wear it. Finally, The Fighter ended the debate.

“If it was up to his brother there wouldn’t be no fight,’’ King said. “It’s easier for those not taking the punches to say no. Barrera stood up and said ‘Let’s go!’

“I was disappointed when they took that fight. I shouldn’t have let him but the guy had given his word to his people. He laid that on me and I had to let him go do it. Then he comes back cut and reality is staring me in my face. Everything I told him came true. They switched opponents on him. He could have got out of the fight but he wanted to keep his word. It may be a blessing though because he came back contrite and more committed.

“He laid into his brother’s ass. In the line of fire you ain’t got no moratorium. His brother said, ‘You ain’t getting no money!’ Marco said, ‘I’ll fight for what Don says.’

“Churchill said ‘This is the beginning of the end or the end of the beginning.’ That’s what it is for Barrera. A new beginning.  After he beats Khan he’s going to be renewed and resurrected.’’

Either that or he’s going to be bruised and sadly affected because if he loses to Amir Khan the lightweight title shot he wants so badly will go with him. That is a thought that Marco Antonio Barrera refuses to entertain.

He bristles at the suggestion this fight is about Khan and not him. Although he understands the consequences of defeat at this stage of his career, he still sees only victory.

Saturday night in England, far from where it all began for him in Mexico, Marco Antonio Barrera will measure himself one more time. He expects to learn he still fits in a most savage workplace.