Jamaica is the 138th most populous nation in the world. At 2.65 million souls, the Caribbean island nestles between Kuwait and Mongolia in the population ladder.

It is in similar territory when it comes to national wealth.

The United States, on the other hand, is the world's richest and third most populous country.

As neighbours go, these two live at very different ends of a very long street.

But there is one place where these two meet as equals - the running track.

Last weekend witnessed the most recent chapter in their rivalry as both countries staged Olympic trials for the 100m in Beijing this summer. The results, as they have been all season, were remarkable.

First, Tyson Gay, the latest sprint star off the US assembly line, almost made the most embarrassing mistake of his hitherto impeccable career by misjudging the finish of his opening heat.

Thousands of miles to the south, world record-holder Usain Bolt and Asafa Powell, the man he deposed, were advancing smoothly to their much-anticipated clash in the Jamaican capital, Kingston.

Bolt was relatively pedestrian in Saturday's 100m final at the trials as he floated to a 9.85, but it was still fast enough to provide another reminder to Powell that he - for now, at least - plays second fiddle at home and abroad.

While Bolt was busy winning his country's 200m title, Gay shot back with a scintillating performance in the American 100m final.

The quiet man from Arkansas, who had already clocked a national record of 9.77 in the quarter-finals, posted the fastest time ever.


A clash between Gay and Bolt should provide a highlight of the Olympics

His mark of 9.68 was pushed along by a 4.1 metres per second tailwind - more than twice as strong as is permissible - so it did not count officially but it will have been noted in the Caribbean (along with the five other American sprinters under 10 seconds).

As Gay's coach Jon Drummond put it: "We need to get some kind of flame-retardant uniform in case he catches on fire, he's running so doggone fast."

Wind-assisted or not, Gay's riposte could not have come at a better time for him, his team or his sport.

Competition between the US and Jamaica across all the sprint disciplines, men's and women's, has been raging for the last four years. And at times, that tussle has provided the only relief to an unremitting diet of gloom for the sport.

Doping has been the only story guaranteed to attract the US media's attention and the drip, drip of credibility draining away became a full-blown haemorrhage when first Justin Gatlin and then Marion Jones were revealed to be drugs cheats.

Gay, who has gone to great lengths to prove his times are legitimate by volunteering for a battery of extra blood and urine tests, stands as proof there is still life in the patient but it needs the oxygen of publicity a great Olympics can provide.

Victory for a certifiably clean Gay in the 100m would go a long way to repairing the damage others have done.

It is also an event the Americans have owned. Four years ago, when Gatlin's chest broke the tape of the closest Olympic 100m in memory, he was maintaining a proud tradition.

So when Gatlin failed a test in 2006 he unpicked the stitches in a wound the sport had been struggling to close ever since the words Bay Area Laboratory Cooperative (Balco) entered every sports fan's common parlance.

Jamaica's biggest challenge over the years has not been doping scandals, it has been holding on to its most talented sons and daughters - Donovan Bailey, Linford Christie and Sanya Richards are just three Jamaican-born sprinters who have won Olympic golds for adopted countries.

The likes of Bolt and Powell are now nurtured by coaches as good as any abroad. While the facilities are still basic, the raw material is now staying at home and flowering more frequently.

Clouds do still remain on the Jamaican horizon, however. Perhaps the biggest concern for outside observers is the lack of a fully functioning anti-doping body on the island.

First mooted in 2005, the Jamaican Anti-Doping Commission (Jadco) remains an organisation with more good intentions than testing kits. Repeated promises have been made to fast-track the necessary legislation and funds through parliament but three years later all that is clear is the island's sprinters are faster than its lawmakers.

Neither the World Anti-Doping Agency (Wada) nor the Jamaican authorities have been able to confirm to BBC Sport that Jadco is actually operating yet. The situation is further muddied by Jamaica's decision to opt out of the Wada-approved Caribbean Regional Anti-Doping Organisation (Rado).

The only organisation currently undertaking widespread testing in Jamaica is the International Association of Athletics Federations (IAAF).

The Monaco-based governing body has raised its game in recent years, and now actively targets countries without adequate anti-doping regimes of their own (Jamaica is the IAAF's fifth most tested nation), but question marks remain over the effectiveness and transparency of its operations.


The drip, drip of credibility became a haemorrhage when Justin Gatlin and Marion Jones were revealed as drugs cheats


Dr Adrian Lorde, the head of the Caribbean Rado which Jamaica stayed out of, has voiced concerns about the amount of testing done on the island.

When asked by BBC Sport if Jamaica was testing enough, he replied: "I don't get that impression. I would like to think they do that testing there but I really don't know.

"I don't know what level of certification their doping control officers have. We really don't know what is going on in Jamaica.

"I am concerned they don't have the programme in place they should have based on the amount of success they have.

"There has been talk about a national anti-doping organisation in Jamaica for many years but it is not functioning yet, as far as we can tell.

"I don't have any worries there are athletes in Jamaica who are cheating, but you only know if it's tested."

Andy Parkinson, who heads this country's anti-doping regime, agreed.

"It worries us that any nation doesn't have an anti-doping organisation," Parkinson told BBC Sport.

"We're committed to making sure there is effective testing in the UK but the fight against doping has to be worldwide."

The authorities in Jamaica, however, vigorously deny their athletes are not being tested enough or as efficiently as athletes from other countries.

Neither Bolt nor Powell has ever failed a drugs test and Bolt alone has passed at least six tests this year.

Dr Herb Elliott, a member of the IAAF's medical and anti-doping commission, said: "We couldn't have the Asafa Powells and not test them. The good name of this country cannot be sullied by this.

"Because of the money in athletics now there is always temptation. So we are aware and vigilant.

"I trust nobody, OK? And I think the federation feels the same way, but that is why we're doing testing we're doing. We're also asking Wada to come down and strengthen what we're doing.

"Some of the athletes are complaining they're being over-tested but we prefer that than no testing at all."

Elliott's stance was reiterated by Mike Fennell, the head of the Jamaica Olympic Association.

He admitted no testing was being done by any government agencies but stressed rigorous checks were conducted, administered by the IAAF.

Whether this third-party testing is enough to convince everybody is debatable. Recent events have not just provoked suspicion of the athletes but the testing regimes have also been found wanting.

It is difficult to suspend disbelief when you remember Jones, to name just one, never failed a test in her long career of systematic drug use.

But what is without question is how central the 100m remains to the sport's future health. As long as men like Bolt, Gay and Powell retain the ability to thrill, and thrill clean, sprinting has a future at the heart of the Olympics.