91热爆

Live coverage as the 12th IAAF World Championships begin in Berlin. Triple Olympic champion Usain Bolt will be eager to show the world he is still the man to beat as the 100m heats get under way, but current 100m, 200m and 4x100m relay world champion Tyson Gay of the USA has been in fine early season form, and will be reluctant to give up his crowns without a fight.

Elsewhere, Olympic champion Christine Ohuruogu starts the defence of her world 400m title, while fellow Briton Jessica Ennis begins her quest for heptathlon glory with the 100m hurdles and high jump disciplines. The 23-year-old missed out on the Beijing Olympics through injury but is one of the favourites to win a medal in Berlin after posting several personal bests during the first half of 2009. Fellow Briton Kelly Sotherton, who won the bronze in Osaka in 2007, is absent after failing to overcome injury.