The United States will get a second chance to qualify for the women's 4x100 meters final after appealing against their disqualification in their heat after a bungled handover.
The reigning Olympic champions and world record holders will run a separate heat on Thursday evening and have the chance to qualify for the final if they achieve the qualifying time after arguing that Allyson Felix was impeded just before the second handover.
"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."
The Americans claimed Brazilian Franciela Krasucki bumping Felix before the handover 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 teammate 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.
"The US team will have a re-run alone, in the same lane, this evening at 20:00, to attempt to qualify by time."
The most likely beneficiaries of the absence of the Americans would be Jamaica – and in particular Elaine Thompson.
Shelly-Ann Fraser-Pryce anchored them to victory in the first heat in 41.79, opening the door for Thompson to sweep the sprint medals at the Rio Olympics.
Thompson won the women's 200 meters on Wednesday to add to the 100-meter title she took from Fraser-Pryce earlier in the week and allowing her a shot at matching Usain Bolt's feat of the last two Olympics.
"We are putting things together well but we'll have to change a few things for the final," said Jamaica's Veronica Campbell-Brown.
"There will be some changes that you will see tomorrow, Elaine will definitely be on."
The Jamaicans needed Fraser-Pryce's blistering finish to hold off Britain, who were second-fastest overall in 41.93, ahead of Germany, who won the second heat in 42.18 once the Americans had effectively eliminated themselves.
Ukraine finished third in the first heat in 42.49 with Nigeria, Trinidad and Tobago, Canada and China also going through to the final.
Dafne Schippers' hopes of a relay medal to add to her silver from the 200 meters were also dashed when the Netherlands managed only sixth place in the first heat.