By Aimee Lewis and Amanda Davies

CNN

(CNN) -- He is the undoubted superstar of athletics, a man who has transcended his sport and will be remembered as a great. But eight-time Olympic champion Usain Bolt has warned that one individual cannot save his sport once he has retired.

Bolt, the 100m and 200m world record holder, has been the dominant figure in athletics for almost a decade. But he will be competing for the last time at the World Athletics Championships in London, which begin Friday.

"It's all about the athletes. The athletes really understand where the sport is at and what they have to do it'll be fine," Bolt told CNN.

In tipping Olympic 400m champion Wayde van Niekerk as track and field's next superstar, he also cautioned that other athletes must take up the mantle he will leave behind.

"Wayde has really picked up, is breaking world records, he's running fast, he's doing a lot for the sport at such a young age.

"He's just 24 so, for me, he will take over without a doubt and he says he wants to be a sprinter.

"If he runs 100m and 200m, hopefully, he'll run fast times and get some energy back and other athletes can see where they can also help," added Bolt.

Athletics is in transition

Bolt will line up in the 100m heats on Friday, with the final to be held at the Olympic Stadium on Saturday.

He is also expected to compete in the 4x100m relay on August 12 before retiring as the most successful sprinter in history.

Such has been the Jamaican's influence on track and field that Sebastian Coe, president of track and field's governing body the IAAF, said this week that Bolt's impact on athletics is comparable to what Muhammad Ali achieved in boxing.

But Bolt warned that the doping which have blighted the sport must stop for athletics to survive.

Bolt is the only athlete to feature on the list of the 30 fastest 100m times ever ran who has not failed a drugs test.

"One thing I hope they understand is that we have a doping problem and if they continue in that way the sport will die and hopefully they understand that," said the 30-year-old.

"They have to just move forward and work hard and be clean and do it as best as possible.

"One person can help keep the sport up, but to keep the sport alive, one person cannot do that.

"Everybody in the sport needs to understand if they don't stop the sport will go. Now we're in the transition phase, the sport is looking for somebody else and if they don't understand that and they start going backwards then the sport will be in terrible trouble.

"But if they go forward with the performance, and make people enjoy watching with laughter and fun, the sport will develop and get better and more and more athletes will start producing and everybody will enjoy the sport."

Bolt's achievements are unparalleled. He is the first man to win the 100m Olympic title three times, while no-one can match his 11 World Championship gold medals.

He ended the Rio Olympics having achieved the "triple triple" of sprint events (100m, 200m and 4x100m.)

But the relay gold won in 2008 was taken away from him this year after teammate Nesta Carter tested positive for a banned substance.

Bolt's dominance is such that he is unbeaten since 2013, when American Justin Gatlin crossed the line before him in a 100m Diamond League race in Rome.

But the sprinter has not been at his best this season, dipping under 10 seconds just once over 100m.

Defiant, he told reporters his career will end his career as 100m world champion.

"If I show up at a championship you know I'm fully confident and ready to go," he said.

"I'm confident in my abilities always because I know when I'm out there I'm ready to go. I'm not worried.

"It's a championship, it's a final. It's all about who can keep their nerves. I've been here many times. I know I'm ready. It's go time."