It was daylight robbery. The man tried to barge open the door, but the preacher stood firm. That was when the shot rang out, splintering the door and searing through his face. Still he held his ground, refusing to buckle and holding his son, and future 100 metres world record-holder, in his bloody arms. “I have been through a lot,” Asafa Powell said.

The Jamaican has had to contend with bullets and brickbats, murder and mockery on his way to the top. Others are trying to beat down his door and steal his crown, with Usain Bolt, the compatriot who used to call Powell “The Fast Man”, and Tyson Gay, the United States sprinter who ran a wind-assisted 9.68sec last week, usurping him. The record has gone to Bolt, the World Championship title went to Gay in a race for which Powell was accused of lacking bottle. It is an allegation at odds with his background.

Exhibit A: “I was on my first full year on the tour when the news came through that my brother Michael had been shot and killed in a New York taxi. I heard the news when I was on the way to the Jamaican trials. That was so hard. I thought about quitting. I did not know if I wanted to do this. Then another brother, Donovan, rang from the States and told me I had to keep on running. It's what Michael would have wanted.”

Exhibit B: “That was 2002 and a year later Donovan collapsed with a heart attack while playing American football. He died. I did begin to wonder which one of my brothers would be next.”

Bruce James, a confidant of Powell and the man who co-founded the MVP Club (Maximising Velocity and Power) in Kingston to plug the drain of Jamaican sprinting talent to the United States, knows how hard that period was. “When two brothers die within a year then that's truly traumatic,” James said. “But the family said, ‘We need you to run and bring some joy back into our lives.' Better run than stay at home and all mourn together.”

So Powell ran. He ran so well that in Athens in 2005 he broke Tim Montgomery's world record by running 9.77sec. He equalled that time twice the next year, briefly had to share the record with Justin Gatlin, who has since been banned for four years after testing positive for testosterone in 2006, and then, last September, ran 9.74sec in Rieti, Italy, to claim the record outright. Lionised in Jamaica, he smiled when Bolt lowered his time to 9.72sec last month.

“Usain taking the record is a great weight off my shoulders,” Powell said. “I am happier being the underdog. Tyson is obviously in good shape, but has had to peak for the US trials [Gay suffered severe cramp in a hamstring at the trials on Saturday and failed to qualify for the 200 metres in Beijing]. I don't want to be running 9.7 yet. I want to build up slowly.”

Time will one day stand still in sprinting, but Powell thinks that there is some way to go. “I think a natural human being can run below 9.7, but we will not go much faster than that unless they put an escalator on the track,” the 25-year-old said. “There is a definite limit to what a human can achieve, unless he is using something.”

There has been a squalid drug den of users in the past and Powell, Gay and Bolt are taking the blue riband sprint to its apotheosis at a time when cynicism has never been more ingrained. Three of the past five Olympic champions have failed drugs tests, while Jamaica invites suspicion by lacking its own anti-doping federation and relying on IAAF testers.

Powell is not one of those athletes who pretends that all is well. Can he be sure that his competitors are clean? “I cannot speak about anyone apart from myself,” he said. “The people running the sport should do something. They need to make the deterrents tougher. A two-year ban does not seem much. I'm no scientist, but they need to work harder, too. I don't know if it's getting worse, but I do know it's not getting better.”

He believes that Dwain Chambers, the British sprinter, should be allowed to run at the Olympic Games because he has served his two-year ban, but thinks that Montgomery, banned, retired and admitting last week to distributing heroin, is “beyond bad”.

Represented by SIML, a London-based management company, Powell should be a global star, but the stain of drugs has tainted all. “I know people will be looking at us three and saying things and pointing fingers, but they don't know the work we put in.”

That work is done at what James calls “third-world facilities” in Jamaica, alongside athletes recruited from the second tier because the best ones have left for scholarships at American colleges.

Powell, though, says that he will never leave Jamaica, where his preacher parents William and Cislin live, but is frustrated with the privacy denied him by his status. “Jamaica is a difficult place to live,” he said. “There are a lot of people on the street. Some don't want to work. They are idlers. They prefer to wait until they see a rich man and then go and beg for something. The people running Jamaica don't care. People come up and ask for things and I usually give them something, but I have no trouble from the gangs. I'm the most famous man in Jamaica, so they don't touch me.”

James says that the only race in which Powell let himself down was at last year's World Championships in Osaka, Japan, where he finished third. Powell says that injuries had limited his races beforehand. “I wasn't ready technically,” he said. “I was faster at the time than everybody there, but I never executed well. I got to 50 metres and something flashed in my head saying, ‘Normally you're further than this.' I tried to pull away. I should have kept my rhythm and composure, but I tried to run faster than him [Gay].”

The lack of medals rankles. Fifth at the 2004 Olympics, his preparation this time has been marred by injury, although his agent has denied that he had shoulder surgery. The layoff, Powell thinks, could serve him well. He said that he “cruised” to 9.90sec at the Jamaica trials on Saturday. “My legs are not as strong as they should be and my arms are weak,” he said. “There is more to come. A lot more.”

The big three

Asafa Powell (Jamaica)

Born: November 23, 1982

Coach: Stephen Francis

Personal best: 9.74sec (2007)

Honours: 2006 Commonwealth Games gold (100metres, 4x100metres relay), 2007 World Championships bronze (100metres), silver (4x100metres relay)

Form: Injury-plagued, but ran 9.90 at the Jamaican trials on Saturday

Usain Bolt (Jamaica)

Born: August 21, 1986

Coach: Glen Mills

Personal best: 9.72 (2008)

Honours: 2007 World Championships silver (200metres, 4x100metres relay)

Form: Breathtaking. Broke world record with 9.72 last month in only fifth race at 100metres

Tyson Gay (US)

Born: August 9, 1982

Coach: Lance Brauman, Jon Drummond

Personal best: 9.77 (2008)

Honours: 2007 World Championships gold (100metres, 200metres, 4x100metres)

Form: Ran the fastest 100metres in history (9.68) at US trials last Sunday, but with illegal tailwind

Scheduled races: July 22 Powell v Bolt (DN Galan, Stockholm). July 25 Powell v Gay (Aviva London Grand Prix), now in doubt. Aug 16 Powell v Bolt v Gay (Olympic final).