Whatever is happening in the fast-moving Olympic world there's one constant: Usain Bolt's bravado and self-confidence. It's what is expected from the world's fastest man and greatest showman.

"I know the sport needs me to win and come out on top," Bolt said as he looked ahead to the Rio 2016 Games.

As for his defence of three Olympic gold medals next month, a so-called 'triple triple,' Bolt is adamant: "I'm not going to lose one of the golds, for sure."

In his last lengthy media appointment before heading to Rio de Janeiro, Bolt spent around two hours over a Jamaican lunch last week in London, discussing his Olympic prospects.

'I always have little doubts'

His preparations for the defence of his Olympic titles (100, 200 and 4x100-metre relay) have been far from smooth, with a hamstring injury forcing him out of the Jamaican trials.

His biggest rivals in Brazil are set to be American duo Justin Gatlin and LaShawn Merritt, who have run the fastest times this year in the 100m (9.80 seconds) and 200m (19.74) respectively. Bolt holds the 100m (9.58) and 200m (19.19) world records.

"I always have little doubts in my mind," he told Associated Press. "But I'm focused and ready to go."

Usain Bolt proves fitness for Rio 2016 by cruising to 200m win in London

Bolt celebrates in typically extravagant style after winning a 200m race in London 22 July (Photo: Getty Images/Christopher Lee)

Long-time coach Glenn Mills has offered the comforting reassurance Bolt still craves. "My coach always tells me that the older you get, it's going to get harder, and you have to push yourself."

Bolt remembers Mills telling him "don't worry you're a champ" at the world championships last year.

It was "one of the roughest years," Bolt said, explaining how his back issue "has really deteriorated over the years."

"At the start of last year I noticed that injuries take a little bit more time to get back to where you want to be."

Justin Gatlin vows not to get ‘sucked into the hype’ against Usain Bolt at Rio 2016

Bolt expects Rio to be his last Olympics, but he has still not ruled out the possibility of a trip to Tokyo.

"My coach always says 'Usain you can always go on to the 2020 Olympics if you want,'" Bolt said. "So this is why he tells me to stop talking about retirement and just take it a year at a time."

When Bolt eventually hangs up his running shoes, there is no doubt that the power of athletics to attract huge worldwide audiences will be more difficult without its global superstar.

"People always say to me, 'Usain when you leave the sport, the sport is going to go down.

"But I'm not going to look at it like that. There are a lot of athletes stepping up."

Still, Bolt is certain that he will be missed when he is gone.

"In football you have the debate who is the best footballer, but no one can debate who the fastest man in the world is," Bolt said.

"It's going to be a long time, I think, before somebody comes who will be as talented as me to break my records."