Gabby Logan presents live coverage from Doha as Norwegian wonderkid Karsten Warholm attempts to defend his World Championship title in the men's 400m hurdles. Warholm captured the imagination in London two years ago with his surprise triumph and warmed up for Doha by clocking the second-fastest time ever in Zurich last month.

America's Rai Benjamin and Qatar’s home favourite Abderrahman Samba are also gold medal contenders in what could be one of the big races of the Championships.

Elsewhere, Britain's former European champion Lynsey Sharp is hoping to claim a medal in an 800m contest without ineligible reigning champion Caster Semenya. Show less