Usain Bolt has warned dopers they risk killing athletics and urged them to clean up their act for the sake of the sport.
The 30-year-old pleaded for clean sport ahead of his final individual 100 metres race at the World Championships this weekend.
Of the 30 best 100m times, 21 were achieved by athletes who have served drugs bans – with the other nine all coming from Bolt during a nine-year career which has earned eight Olympic gold medals and 11 world titles.
Athletics has been under a cloud, with the Russian federation banned for systemic doping since November 2015.
Several British athletes are also due to get medals which they lost out on because of dopers during the championships this month.
Sheffield’s Jessica Ennis-Hill is to be awarded World Championships gold after Russia’s Tatyana Chernova was stripped of her 2011 crown.
And Bolt, who holds the world records in the 100m and 200m, insisted dopers are endangering the future of athletics.
He said: “Hopefully athletes will see what’s going on and understand that if they don’t stop what they’re doing the sport will die. Hopefully, they will understand what the sport is going through and what they need to do as athletes to help the sport move forward.
“Personally I think it was there (rock bottom). After the scandal on Russia I don’t think it gets any worse than that. It’s on its way back up now.
“You can’t be happy about doping at all, it’s not good for the sport. But 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, listen, 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. The only way track and field has left to go is up. We’re going to go in the right direction and I’m happy about that situation.
“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.”
Bolt was speaking in London for the final time ahead of Friday’s 100m heats and Saturday’s semi-final and final as he aims to defend his world title from Beijing.
He will also race in the 4x100m relay next week before bringing the curtain down on a stunning career. Yet his preparations were hit when close pal and British high jumper Germaine Mason was killed in a motorbike accident in April following a night out with Bolt in Jamaica and Bolt wants to bow out winning for his friend.
“For me it was a rough time. I have never had someone who passed away so close to me. It set me back a little bit and I didn’t train for three weeks maybe,” said Bolt.
“And my coach gave me my space, he gave me my time to get over it. But at some point just the close net of people I was with said ‘listen to us Usain, I know it is hard but you need to get back training because Germaine would have wanted it’.
“He was looking forward to coming to your last race and seeing you compete and finishing off your legacy. So for me that really helped me get going again. It was hard but now I really want to do it also for him and his family and all the friends that supported me.”
Bolt insists he was ready for London – where he first defended his Olympic titles in 2012 – and wants his legacy to stand the test of time.
He said: “Unbeatable. Usain Bolt has retired unbeatable over that event. For me that will be the biggest headline - unbeatable and unstoppable.”