He has been acclaimed as the greatest athlete the world has ever seen after winning a historic ninth Olympic sprint gold medal.
But Usain Bolt's unique 'triple triple' of Olympic titles could be a short-lived achievement with his Beijing relay medal under threat of being stripped after a team-mate reportedly failed a retrospective doping test.
Nesta Carter ran the first leg for Jamaica's 4x100m team when Bolt anchored them to a gold medal inside Beijing's Bird's Nest stadium at the Olympic Games where he announced himself as a sprinting superstar.
If Carter is confirmed as a drugs cheat, it would present the devastating possibility of all four men in that team losing their gold medal. There is no suggestion the remaining three men have done anything wrong.
On Friday in Rio, Bolt completed an unprecedented 'triple-triple' of 100m, 200m and 4x100m titles at three consecutive Olympics.
At London 2012 Carter was in the 4x100m team - again anchored by Bolt - which won gold in a world record time of 36.84sec although that medal is not thought to be under threat.
Sources told Sportsmail 30-year-old Carter - the sixth fastest man in history - was one of 31 athletes to return adverse findings when blood and urine samples taken at the Beijing Olympics were retested using more sophisticated techniques.
The 30-year-old, who has also won three 4x100m World Championship titles alongside superstar Bolt, is thought to have tested positive for the banned stimulant Methylhexanamine.
He has already been notified that his 'A-sample' has come back positive but his 'B-sample,' an extra urine or blood sample taken at the same time as a safety net, which was still to be opened in June.
If the B-sample returns positive then Carter, who ran a 9.78sec 100m in 2010, may face sanctions which could include a ban of up to three years and being stripped of medals. It would also leave Bolt, whose world record is 9.58sec, as the only man to have run under 9.79sec who is not tainted by a drugs ban.
The other four - Tyson Gay (9.69sec), Yohan Blake (9.69sec), Asafa Powell (9.72sec) and Justin Gatlin (9.74sec) - have all been done for doping violations. Neither Carter nor his agent replied to repeated requests for comment.
The International Olympic Committee, which carried out the targeted retesting of 454 samples from the 2008 Games in a bid to clean up Olympic sport, previously declined to comment, as did Jamaica Olympic Association president Michael Fennell.
So far only 14 Russians and one Spaniard have been outed as among 31 sports-people who have retrospectively tested positive and Carter would be the biggest name to be exposed.
It would be the latest in a spate of high-profile drugs bans for Jamaican athletics in recent years. Powell and Sherone Simpson were banned for six months after testing positive for a stimulant in 2014.
And the revelation that the Jamaican Anti-Doping Commission carried out just one out-of- competition test between March and July before the London Olympics called into question doping controls on the island.
Methylhexanamine has been on the World Anti-Doping Agency (WADA) Code prohibited list since 2004, although it was reclassified on the 2011 list as a 'specified substance'.
WADA defines specified substances as those that are more susceptible to a 'credible non-doping explanation,' so even if Carter is confirmed as having tested positive he may use this in his defence.
Meanwhile, organisers of the 2018 Gold Coast Commonwealth Games will do all they can to convince Usain Bolt to extend his career to race in their event.
Bolt made Olympic history today when he completed a unique triple-triple, winning gold in the 100 metres, 200 metres and 4x100 metres relay in three successive Games.
The 29-year-old has indicated he will retire after the 2017 world championships in London, but Gold Coast 2018 Commonwealth Games Corporation chairman Peter Beattie hasn't ruled out persuading the Jamaican superstar to change his plans.
Bolt has only once competed in the Commonwealth Games, helping Jamaica win the 4x100m relay in Glasgow two years ago as part of a promotional deal involving Virgin Media.
Beattie says whether a similar deal could be struck to bring him Down Under is unknown but organisers will be discussing their options when they meet the Commonwealth Games Federation in October.
"We'll explore whatever avenues we can to encourage him to come here," Beattie told AAP.
"He'd be a magnet for Queensland, a magnet for the Commonwealth Games."
Bolt's appearance in Glasgow was overshadowed by a row between him and The Times newspaper.
The Times reported that Bolt called the Commonwealth Games "a bit shit". Bolt said the story was "nonsense" but the Times stood by its reporting "100 per cent".
- additional reporting AAP and staff reporter