World 100 metres champion Justin Gatlin says he is "shocked and surprised" by allegations in a British newspaper that his coach and an athletics agent offered to sell performance-enhancing drugs to undercover reporters.

Four-time Olympic champion Mo Farah ends his track career in thrilling fashion with victory in the 5,000m at the Diamond League final in Zurich while world 100m champion Justin Gatlin slumps to defeat.

A sentimental Justin Gatlin hails Usain Bolt as an "amazing showman" whose career would certainly not be defined by him pulling up with cramp in the world 4x100m relay, the Jamaican's final competitive race.

Usain Bolt rues a disastrous start as his failure to fire saw American arch-rival Justin Gatlin poop what was supposed to be a party in his final 100m race at the world championships.

They finished second and third in last year's Olympics 100m final and on Friday Justin Gatlin and Andre De Grasse renew their rivalry in the Diamond League season-opener in Qatar.

Evergreen American sprinter Justin Gatlin struck gold when he anchored his team to victory at the IAAF World Relays in Nassau, while double Olympic champion Elaine Thompson shone for Jamaica.

Usain Bolt will race the 200m final on Thursday after comfortably winning his semi-final, but there is no place for American rival Justin Gatlin as he fails to qualify.

The battle to be crowned world's fastest man takes centre stage at the Rio Olympics on Sunday with Usain Bolt facing another showdown with Justin Gatlin where the image of athletics will be on the line.

Usain Bolt is promising to let American sprinter Justin Gatlin "feel his full wrath" as he zones in on an unprecedented treble of gold medals.

Justin Gatlin fully expects ailing world record holder Usain Bolt to be ready for another 100 metres showdown at the Rio Olympics.

American Justin Gatlin roared to a 100 metres victory in Japan on Sunday, as track and field's pantomime villain kicks off his preparations for this summer's Rio Olympics.

Six-times Olympic champion Usain Bolt has already started his preparations for next year's Rio Games and wants to break 19 seconds in the 200 meters.

Usain Bolt beats Justin Gatlin for the world 200m title at the championships in Beijing, China.

Usain Bolt’s focus turns immediately to the 200m, in which he will be seeking a fourth consecutive title after having previously triumphed in Berlin, Daegu and Moscow.

Usain Bolt beats Justin Gatlin by one hundredth of a second to retain the 100m title at the World Athletics Championships in Beijing.

Jamaican sprint star Usain Bolt expresses his sadness that doping issues are the talking points before world championships at Beijing.