LaShawn Merritt, the US world and Olympic champion over 400m, sets the quickest time this year in his heat. Mark Ralston / AFP
Liu Xiangrong of China in mid-rotation during her throw in the women's shot putt. DIEGO AZUBEL / EPA
Athletes compete in one of the heats for the women's 1500m event. Chris McGrath / Getty Images
Decathletes relax during the discus event of their 10-event competition. DIEGO AZUBEL / EPA
The leaders of the men's 20km walk, including the eventual winner Valeriy Borchin of Russia, pass through a "spray station" during their gruelling event on the streets of Daegu. Kim Jae-hwan / AFP
Pistorius, known as "Blade Runner", finished third in his 400m heat and will compete in tomorrow's semi-finals. DIEGO AZUBEL / EPA
The South African double amputee Oscar Pistorius settles down into his blocks during his 400 metres heat. DIEGO AZUBEL / EPA
The Chinese 110m hurdler Liu Xiang jumps a hurdle during his heat. Kevin Frayer / AP Photo
A South African fan celebrates Oscar Pistorius' success in the 400m event at the world championships in Daegu. David Gray / Reuters
New Zealand’s Nikki Hamblin falls in the women's 1500m heat as the pack moves on. Martin Meissner / AP Photo
A pole vault competitor chalks in preparation for one of her attempts. David J Phillip / AP photo