Jamaican superstar Usain Bolt believes the world of athletics is slowly winning the battle against doping.
The Sprint King is in London ahead of the 2017 World Championships, which starts on Friday.
"Over the years we're doing a better job, it's getting clean and we're catching up to a lot of athletes," the 30-year-old told BBC Sport.
"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."
Bolt added that the Russian doping scandal ahead of the 2016 Olympic Games was arguably the lowest point in the sport's history.
"Personally I think we were at rock bottom…after the scandal on Russia I don't think it gets any worse than that," continued the eight-time Olympic gold medallist.
"Hopefully athletes will see what's going on and what they need to do to help the sport move forward."
Bolt will compete in the 100m on Saturday and the 4x100m the following Saturday in London.