As he reflects on the role he played in turning a skinny rural boy into one of the world's wealthiest sportsmen, who will earn US$100 million from the Las Vegas fight alone, he talks of the boxer's boyhood as if it were yesterday.

In his autobiography, Pacquiao - now 36 and the first fighter in history to be crowned champion in eight weight divisions - writes warmly of his debt to Mejia. He describes watching Mike Tyson's shock defeat to James "Buster" Douglas in 1990 on television with his uncle as an experience that "changed my life forever".

"I knew without a doubt I would become a fighter," he writes. "I knew that the underdog can, and often does, win."

With the enthusiasm of an armchair fanatic who had finally found an outlet for his passion, Mejia threw himself into training his young charge, transforming a room of his home into a makeshift gym.

"For Uncle Sardo, it was the ultimate blessing that his little nephew shared his favourite hobby," Pacquiao writes. "Even though he had no formal training, we both took it seriously and knew that we were going to be champions one day."

Training the wiry youngster, who moved from the remote southern coast of Mindanao into Uncle Sardo's home with his family, was no easy task at first.

"When he started, he had no muscle on him at all and I couldn't see him ever becoming a fighter," recalls Mejia. "Then, after I trained him for six months, I said to myself: 'This boy is going to be a world champion'."

What set Pacquiao apart were his attitude and a hunger to succeed.

"He always had great self-discipline," says Mejia. "He learned everything so fast. He practised all the time and he would get up at 4am to go jogging.

"I used to go out and rent videotapes of Mike Tyson fights and show them to him. He picked up the tactics so quickly. At first his mother didn't want her son to be a boxer. She said, 'I want him to be a priest.' But Manny told me he wanted to become a boxer because his family was very poor. He had no money to study in school or college."

Pacquiao began boxing in an open-air park in General Santos, beating all-comers. He then travelled to Davao City, 150km away, to take on higher-ranked opponents. Within three years, he had established himself as the best junior boxer in the southern Philippines.

At the age of 15, he stowed away on a boat to seek out greater challenges in the capital, Manila, sleeping on the streets and inside the boxing ring of a gym as he continued his training.

Pacquiao's transformation from scrawny school dropout to junior boxing champion is just one of the chapters in an astonishing rags-to-riches story that makes the working-class boxers who famously rose from the ghettos of post-war America seem almost to have been born with silver spoons in their mouths.

Until the age of 10, Pacquiao had never seen a TV set and had never set foot in a town or city. He lived with his parents, sister and two younger brothers in a single-room shack in Tango, in a rugged landscape of coconut groves, dense jungle and coastal mountains some 50km south of General Santos. The boxer - who is reportedly buying a US$12 million Beverly Hills mansion once owned by rapper Sean Combs - lived a life of abject poverty. His father, Rosalio, would clamber up as many as 70 trees a day to gather coconuts, struggling to earn enough to feed his family.

Pacquiao and his family were poor even by the wretched standards of other villagers in Tango. One uncle - Benito Bequilla, 67, who would take him fishing - recalls that they were so hard up they could rarely afford even to eat rice.

Asked about his famous nephew, Bequilla throws back his head and laughs: "Manny is just the same as he always was. He has never forgotten us. God has given Manny all the love and the grace. He always cares for his family and his relatives. I think the world of this man. We are all so proud of him."

In front of Bequilla's house is a fishing boat owned by the boxer and a black and gold fishing net he uses when he visits Tango, where he is now known not only as a famous boxer, but as a congressman, too. Having been elected to represent the Sarangani region in 2013, many people tip Pacquiao as a future president of the Philippines.

"When he comes to visit, we go fishing together for a few hours. Even though he is a famous man and a busy congressman as well, he never forgets. This is his home and he loves to come back here," Bequilla says. "Manny will come to the village and he will take me to one side and whisper in my ear, 'Uncle, I'll give you 15,000 pesos [HK$2,625]', or 'I'll give you 20,000 pesos'.

"When they were growing up, Manny and his family used to collect stale bread and heat it up to sell. They were very poor but we always helped each other. If they had no rice and we had rice, we would share our rice with them."

Emirina Edrina recalls how Manny's mother - a cousin of hers - was loving and resourceful, but strict.

"Once, when he was seven or eight, she tied him to a coconut tree for half an hour and let him get bitten by ants as a punishment for not coming home on time," she says. "He didn't cry.

"The family … lived on bananas and root crops. They had no rice most of the time. Manny wore ragged clothes. It's hard to imagine that he is so rich and famous today - it is like a dream."

Edrina, 47, and her extended family last year moved into a home in a new settlement for 200 families in Tango called Pacman village - Pacman being Pacquiao's nickname.

"He built this village with his money and didn't even charge us one peso for these new homes," Edrina says. "If Manny hadn't helped us, we would be the poorest of the poor. Here, the only work is fishing or collecting coconuts or working as a tricycle driver."

The settlement of simple homes is one of a number Pacquiao has funded in the region. Despite his largesse, however, villages throughout the area remain poverty-stricken and troubled by Muslim insurgents. Tango and other communities are subject to night-time curfews and roads through the region are dotted with police checkpoints, which have proliferated since 44 officers were killed in a shootout with insurgents north of General Santos in January.

As he grew up, Pacquiao's family were taunted for being less well off than most in Tango and his first fight, at the age of nine or 10, was against a boy who teased his younger brother, Bobby, for being "poorer than dirt". Pacquiao floored his brother's tormentor with a single left jab.

Constancia Pelayo, 68, was Manny's teacher in his final year of primary school, when he was 10. She says she believes the discipline - and perhaps occasional beatings - she administered played a part in his later success.

"I am not surprised he is so famous because when I got angry with Manny and his classmates, I told them, 'You can do what you like when you are rich. In the meantime, I am your teacher and you will obey me,'" she laughs.

Pelayo, who retired in 2007 after having taught at Tango primary school for 38 years, says, "You can't educate children without discipline. Sometimes I beat them to make them behave. I can't remember if I hit Manny. Manny was an average pupil. Sometimes he was naughty. Sometimes he was good. There are no perfect children.

"I am proud that I was his teacher, of course. He always comes back to visit the school when he is in the area. He has donated many things to the school, including computer equipment."

Back in General Santos, in a smart neighbourhood 1.5km away from Uncle Sardo's house, Pacquiao's father is overseeing the construction of a luxury two-storey home paid for by his son as he prepares to fly to Las Vegas, where he will have a ringside seat for the big fight. The 56-year-old - who is notoriously shy of the media - agrees to speak briefly about his son's upcoming fight after protracted negotiations with minders through the gate of his new home. Gesturing around him with a smile, Rosalio says, "Sometimes, it's hard for me to believe all this is real."

Dressed simply in shorts and a T-shirt but wearing a gold necklace, watch and bracelet, Rosalio says the stories about Pacquiao's humble background - dramatised in film called (his nickname as a teen boxer), which was released across the Philippines this month - have not been exaggerated.

"Our life was very tough when Manny was young," he says. "Most of the time we had only bananas and root crops to eat, but when I did make more money, I made sure my family ate rice. Now we eat anything we want to eat."

The relationship between father and son has not always been harmonious, however. After the family moved to General Santos, Rosalio left his wife and children for another woman and - Pacquiao later claimed - killed Manny's pet dog. Pacquiao's trainer, Freddie Roach, claimed in a 2009 interview that Rosalio not only killed but also ate the pet.

In his autobiography, Pacquiao writes killing the dog was "even worse" than walking out on the family. "[Rosalio] took the puppy I found and killed it. To a young boy that was unforgiveable - it was stealing something I loved, which is far more terrible than stealing money," he writes. "More than 20 years passed and I couldn't forgive him."

Pacquiao did not set eyes on his father for nearly two decades after the dog's death. In 2009, Rosalio visited the United States to watch a fight, and he was reunited with Pacquiao and his mother.

"I was not bitter or mad any more," Pacquiao writes. "I forgave him immediately.

"Too many years had passed and we both suffered greatly because of one horrible moment in our lives … It was like a soul cleansing to me, like a hundred-pound sandbag had been taken from my shoulders."

Asked about the incident, Rosalio laughs with an air of mild embarrassment and insists: "It isn't true that I killed his dog. I don't know where the story came from … Perhaps it was a misunderstanding."

Appearing to suggest that the story may have arisen from the differences between him and his ex-wife during their bitter split, Rosalio says, "I always supported my son's boxing career in those days. His mother didn't want him to box but I encouraged him."

However, Rosalio confirms he is now much closer to his son and has flown to see him in seven fights since their reconciliation. He proudly shows a picture of Pacquiao with his arm resting somewhat awkwardly on his shoulder at a birthday party for the boxer's grandmother, in General Santos, last year.

"Our relationship today is very strong and very close," Rosalio says. "When we see each other, we hug and then we talk about the fights and tell stories to each other. Manny is always helping people. He is very generous. If someone approaches him to ask for help, he will help. He looks after his parents and he looks after his brothers and sister."

Pacquiao's flamboyant mother, Dionisia, who unlike his father regularly appears on TV and in newspapers and magazines, has a 40-year-old boyfriend and lives in a luxuriously appointed American-style villa on the outskirts of General Santos that is guarded by a gaggle of young security guards in sportswear and baseball caps.

"She can't see you - she's doing a photo shoot," one of the bodyguards tells us at the gate before taking our calling card and disappearing inside.

Like Pacquiao's father, Dionisia will be at the heart of the glamour of the MGM Grand Hotel and Casino in Las Vegas for the Mayweather fight.

For Mejia, however - who is uncannily like a Filipino version of the Burgess Meredith character Mickey the trainer from the films - the setting for the biggest fight of Pacquiao's life will be the rough streets of General Santos, where he first lit the fuse of the boxer's passion for the sport.

"I never went to see him when he fought in Davao so I'm not going to travel all the way across the world to see him fight," he laughs. But with a moving devotion to Pacquiao's career, Uncle Sardo watches every contest and, as he used to do with the Tyson bouts, analyses his every move.

"I believe Manny will win," says Mejia. "If you look at their footwork, Manny is better than Mayweather. If you look at punching power, Manny is better."

Even though he is not part of the lavishly rewarded entourage of trainers and advisers who accompany Pacquiao in his world of mega-stardom, Mejia seems as thrilled as anyone at the spectacle of the scrawny kid he introduced to boxing etching his name on the roll call of the sport's all-time greats.

"Every time I see Manny, I give him some advice about his next fight," he says. "He still listens to me, after all these years. I last saw him in February, when he came back to General Santos. I said to him, 'Don't let Mayweather get too close to you in the ring. Keep your distance'."

His crinkled face breaks into a broad toothy grin as he repeats the response given by a fighter whose career earnings are expected to have topped US$400 million by the end of this fight: "Manny smiled at me and he said: 'Yes uncle, I will bear in mind your advice.'"

Red Door News Hong Kong