LONDON (Reuters) - The injury-enforced absence of David Rudisha has left the door open for the men's 800 metres title at the World Athletics Championships and half a dozen contenders, led by Nijel Amos, will fancy their chances following Saturday's first round.

Botswana's Amos won silver as an 18-year-old behind Rudisha's world record-setting triumph on the same track in the Olympic final five years ago and although he has been an inconsistent performer since then, he arrived in London in good form on the back of three successive Diamond League victories.