US races nobody to snatch position in women's 4x100m final
The United States has clinched a spot in the women's 4x100 metre final, thanks to a unique second chance heat the team ran alone.
The side clocked a 41.77 second time, and knocked China out of the top eight.
They had to beat a time of 42.70 seconds to make the final.
They will join arch-rivals Jamaica, Britain, Germany, Ukraine, Nigeria, Trinidad and Tobago and Canada in the final.
Earlier, the American team was disqualified after baton bungle.
The US team claimed Brazilian Franciela Krasucki bumped Allyson Felix before the handover, which had prevented her from getting close enough to English Gardner to complete the handover.
The baton fell to the ground when Felix threw it in the direction of her team mate but after the initial shock, the experienced Californian had the presence of mind to get Gardner to pick it up and resume the race, allowing the appeal.
"The referee examined the video of the race and agreed that the US runner was obstructed at the second exchange," the IAAF said in a statement.
"I think I got propelled at about 20 miles an hour," said four-times Olympic gold-medallist Felix.
"When a foreign object comes in front of you, it's going to mess up the momentum and the handover."