The Bird's Nest Stadium was the scene of Usain Bolt's explosion on the world scene in 2008 when the Jamaican sprint superstar won gold in the 100 and 200 metres at the Beijing Olympics.

The 28-year-old will be back at the scene of the sublime this weekend as he takes part in the World Championship 100 metres.

But the man who will be challenging him for Sunday's final comes loaded with a baggage of controversy which is not affecting his speed.

Justin Gatlin, who has been twice banned for doping offences, has been the fastest in the world this year, despite being 33 and seemingly past his natural peak.

"What Beijing will provide on Sunday night is something under 10 seconds, one of the most anticipated head-to-head clashes that we've seen," said The Science of Sports' Professor Ross Tucker who joined us on Off The Ball to preview the race in depth.

"And their personalities seem to be so different, the appeal they have is so different. And the other thing that I've looked at is the trajectory of their performance is so different. You've got Usain Bolt who's one month ago was nowhere. I mean, I had doubts that he would even show up in Beijing because he hadn't broken 10 seconds yet. On the other hand, you've got Gatlin, who in May running 9.7 and isn't getting any slower. So many unanswerable questions will come to a head in 9.7 something seconds."