By Mitch PhillipsRIO DE JANEIRO, Brazil (Reuters) – Usain Bolt waltzed in to sprinkle a bucket of stardust over Rio on Monday, and while there were Samba smiles and dancing girls, the biggest name at the Olympics could not escape the ever-present spectre of doping.Bolt is seeking to secure a ‘triple-triple’ in the 100 metres, 200 metres and 4x100m relay and was his usual show-stopping self as top billing in an eye-catching Jamaican team news conference at Barra’s massive Cicada des Arts theatre.But he also had to face up to questions about how and why fans could have any faith in athletics after the battering it has taken on the doping front in the last 18 months.“I think we are going in the right direction. People should have faith,” said Bolt, who won 100m, 200m and 4x100m gold at the last two Olympics.“We are weeding out the bad ones and I personally think we are on the right track. We have had to go through a rough time before the good times. But in a few years, the sport should be clean and I look forward to that.”Last year, Bolt edged out American Justin Gatlin to win the world championship 100 metres final in a race widely billed as “good v evil”, with the Jamaican ‘saving’ the sport from an athlete back in action after two doping bans.Asked if fans could believe they were watching a clean race when the two, if all goes to plan, face off in the 100 metres final next Sunday, Bolt was a touch more diplomatic.“In life nothing is guaranteed,” he said. “But I never worry about drugs. That’s for WADA, the IAAF and the IOC. I go out and compete and wow the crowd and entertain people.”He did say, however, that he supported the governing body’s decision to ban Russian track and field athletes because of the country’s extensive state-sponsored doping.MAKING A STATEMENT“I think they want to make a statement and that’s why they really need to show people that if you cheat this is what’s going to happen,” Bolt told Reuters.“So, for me, if making a statement is going to help the sport, then I will support it because this is what I do. This is my sport and I really enjoy competing, and it would be better for my sport if it is clean.”The Jamaican superstar, who turns 30 later this month, confirmed that this would be his final Olympics but said the lure of the big championships remained strong and in the final weeks of build-up, he really felt focused on the tasks ahead.He has certainly had some work to do as, having missed the 200 metres in the Jamaican qualifiers because of a hamstring strain, he found himself lagging behind where he wanted to be in his preparations.He did manage to fit in a 200 metres at the London Diamond League three weeks ago but though he won in 19.89 seconds, it was hardly a smooth performance — something his coach Glen Mills made sure he was aware of.“I called him and he asked me what I thought and I said I thought it was okay, maybe not a great bend,” he said.“My coach said ‘No, that was one of the worst races you’ve ever run. The bend was awful’ … and he just went on until I was depressed.”In light of those missed weeks of training and some rust around the edges, super-fast times are probably unlikely for Bolt in Rio but, as ever, he remained supremely optimistic.“I really want to run under 19 seconds, that’s my focus. It will be a little bit hard because I missed out on a few weeks of training, but you never know,” said the man who set the world record of 19.19 in 2009.