|World Athletics Championships on the BBC|
|Venue: London Stadium Dates: 4-13 August|
|Coverage: Live across BBC One and Two, BBC Radio 5 live, BBC Radio 5 live sports extra, the BBC Sport website and app.|
Usain Bolt says athletes who dope must "stop or the sport will die" as he prepares to race for the final time in his illustrious career.
Bolt, an eight-time Olympic champion and icon of world sport, will retire after this month's World Championships.
The Jamaican, 30, will run in the 100m and 4x100m at the Worlds, which begin in London on Friday.
"Hopefully athletes will see what's going on and what they need to do to help the sport move forward," he said.
Referring to the McLaren report, which uncovered evidence of a Russian state-sponsored doping programme, he added: "Personally I think we were at rock bottom. After the scandal on Russia I don't think it gets any worse than that.
"Over the years we're doing a better job, it's getting clean and we're catching up to a lot of athletes. There's an understanding that if you cheat you will get caught. Over time the sport will get better.
"I said a couple of years ago it had to get really bad, when there's nowhere else to go but up. Doping is always a bad thing and it's never pleasant because you put in the hard work and the sport starts going forward and then you have other guys bringing it back, it's hard.
"It's going in the right direction so hopefully it will continue in that direction."
'I'm still the fastest'
The men's World 100m final is on Saturday, 5 August, while the men's 4x100m relay race - which will mark the end of Bolt's career - is on the following Saturday.
Bolt has won 100m, 200m and 4x100m gold at the past three Olympic Games - Beijing 2008, London 2012 and Rio 2016.
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However, his unprecedented 'triple triple' of nine gold medals was downgraded to eight after Jamaican team-mate Nesta Carter, who was part of the quartet that won the 4x100m in Beijing, tested positive for a banned substance. Carter has appealed against the decision.
Nevertheless, Bolt's exploits remain unprecedented and he also holds the world record in the 100m (9.58 seconds) and 200m (19.19).
Asked if he still believes he is the fastest in the world, the Jamaican replied: "Yeah, without a doubt.
"The last race I ran was a 9.95, so that shows I am going in the right direction. After the two rounds leading up to the 100m final, which always help me, it's all about who keeps their nerve.
"I have been here many times. I know I am ready."
Asked in an interview with BBC Sport whether he believes his world records will be broken, he replied: "I hope they're not. No athlete would ever wish for that - I want to brag to my kids when they're in their 20s: 'See, I'm still the best!
"There is no-one around now, in this era, who can do it. No. Maybe in a couple of years, 10 years, but my records are safe for now."
Athletics after Bolt
Bolt was also asked which of the current stars of track and field could potentially replace him as the pre-eminent force in the sport.
He named South African 25-year-old Wayde van Niekerk, who will be competing in the 400m and 200m in London.
"Wayde van Niekerk is proving he is a world star. He has broken the 400m world record, he ran the fastest 300m ever, and now he's doing the 200m also. For me, he's proving that he can step up to the plate," said Bolt.
"I'm watching him, we've had discussions and he's a cool person but I've told him to open up his personality a little bit because he's really laid back."
Bolt after athletics
Bolt says he will miss the "thrill" of being on the track but that it is time for him to slow down and enjoy himself.
"The energy when you first walk out on the track and the people go crazy, that's what I'll miss the most," he said.
He might manage to replace the buzz of competing with one of his hobbies, though.
"I ride quad bikes, that's an adrenaline rush," he said.
"But I think it's time for me to slow down a little, relax a little bit. Enjoy myself as much as possible."
He says he does not think he will reconsider his retirement as he has nothing left to prove - and of his legacy added that he wanted to be considered among the greatest sports figures of all time.
"I just want to be one of the greats," he said.
"Whenever there's a conversation about the greatest sports stars, I want to be part of that conversation. I want people to say: 'Yeah, Usain Bolt was one of the greatest'."
Asked if it was his mind or body saying 'enough', he replied: "It's the body, definitely.
"Over the years, I've got more niggling injuries than anything else, simple little things, but it's just because I'm getting older. The pounding means my body's just deteriorating now, so for me it's just time to go."