FASTEST MEN IN THE WORLD
Five of the 10 fastest men of all time have tested positive for banned drugs 1 Usain Bolt (Jamaica) 9.58secs for 100m
The double Olympic 100m and 200m has never failed a drugs test and said last week: "I am clean, I'm sure about that. I welcome people to test me every day if necessary to prove it to the world. I have no problem."
2 Tyson Gay (USA) 9.69secs
The fastest man in the world this year failed a test for an unknown substance and is now awaiting the result of a B sample.
3 Yohan Blake (Jamaica) 9.69 secs
The 2011 world champion and Olympic silver medallist has returned no positive findings.
4 Asafa Powell (Jamaica) 9.72 secs
The former world record holder has tested positive for banned stimulant Oxilofrine and is awaiting the outcome of his case.
5 Nesta Carter (Jamaica) 9.78secs
Part of the Jamaica quartet along with Bolt and Blake who broke the 4x100m world record at the London Olympics. He has a clean record too.6 Ben Johnson (Canada) 9.79 secs (rescinded)
BANNED FOR LIFE
The Canadian tested positive for the steroid stanozolol after winning the 1988 Olympic 100m in world record time. Banned for life by the IAAF after testing positive for excess testosterone in 1993.
7 Maurice Greene (USA) 9.79 secs
Former Olympic 100m champion and world record holder has always insisted he has never used banned drugs.
8 Justin Gatlin (USA) 9.79 secs
BANNED FOR FOUR YEARS
Gatlin was banned for four years in 2006 after testing positive for testosterone. He made a comeback in 2010 and won bronze at the London Olympics, setting a personal best.
9 Steve Mullings (Jamaica) 9.80 secs
BANNED FOR TWO YEARS
Mullings served a two-year ban for testosterone in 2004. He returned to sprinting and a World Championship relay gold in 2009.
10 Donovan Bailey (Canada) 9.84 secs
The 1996 Olympic champion was the world's fastest man for a time, and always referred to drug-takers as "cheats".