RIODE JANEIRO (AFP) - The United States' 4x100m women's relay team won their solo race against the clock to book their place in the Olympic final on Thursday.
The American quartet of Tianna Bartoletta, Allyson Felix, English Gardner and Morolake Akinosun clocked 41.77 seconds to eliminate China from Friday's final.
"Before we came out our coach said it was just like a practice with the whole world watching," a relieved Gardner said after the one-off. "We just had to go out there and trust each other."
Felix added: "It was different, it was really weird. Running without competition is just strange.
"I think when we walked out and people were cheering for us, it encouraged us. We're just grateful."
It completed a surreal day for the reigning Olympic champions, who had earlier been left facing disqualification after a dropped baton exchange between Felix and Gardner in the morning heats.
But the American women were thrown a lifeline when replays showed that Felix had been knocked off-balance by Brazilian runner Kauiza Venancio as she prepared to hand off to Gardner.
The US team filed a protest and race officials duly disqualified Brazil - but ruled that the Americans must run again, in a highly unusual solo flying lap - to beat China's eighth fastest qualifying time of 42.70sec.
The decision angered Chinese officials but their protest was later dismissed by the International Association of Athletics Federations (IAAF).
Felix meanwhile said she was still digesting a crazy day on the track.
"I was stunned and shocked when it happened. I've never been involved in anything like that," she said, adding she had no qualms about the decision which ultimately led to China's relay squad being knocked out of the final.
"I think the process was fair," Felix said. "I was impressed with the plan they came up with. It was just kind of an unfortunate situation. I wouldn't want to bump anyone out of a slot, but at the same time we were impeded. I think it's not ideal."