The destination of the medals in the heptathlon was thrown wide open by the first event of the second day, which leaves just 26 points between second place and fifth, and which saw overnight leader Jessica Ennis, of Britain, have her lead whittled down to just 100 points.
Gayle Hunter, of the United States, sixth overnight, was the best long jumper. Her 5.92m effort in the third round scoring 825pts and moving her to fourth overall on 3951, just 16 shy of a medal position.
There was drama for Germany's Sarah Kern, who had ended day one in the silver medal position. Two foul jumps put her under severe pressure to register some mark in the final round, but she responded magnificently to clear 5.66 and 747 vital points.
Kern's 3971-point five-event total was just four better than Marina Goncharova, the second best long jumper on the day, with 574 and 771pts, to remain in third overall just ahead of Hunter and Brazil's Jailma Sales de Lima, whose 5.72 best jump scored 765pts for a total of 3945.
For the first time in the two-day event, Ennis is beginning to look vulnerable, after only managing to finish ninth in the long jump, her 5.47m best effort scoring 691.
Ennis remains firmly in the lead, her 4071pts being 100 better than Kern and the chasing pack. But with an acknowledged weak javelin, the next event, the heptathlon could all depend on the outcome of the 800 metres later today.