Cate and Bronte Campbell have both missed the podium as Simone Manuel and Penny Oleksiak finished in a dead-heat for gold in the 100m final.
Red-hot favourite Cate finished sixth while Bronte was fourth in just the second 100m freestyle final dead heat in Olympics history.
Heartbreaking. Image: Getty
"I just spent too much emotional energy in the lead-up," Cate said.
"I let my head get ahead of me, it's not something I should do.
"It's hard when you are in form coming into an event not to think about outcomes."
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The sisters had cruised into the final, with Cate qualifying fastest and breaking the Olympic record she earlier broke in the heats.
Manuel and Oleksiak touch in ahead of Cate. Image: Getty
Bronte was fifth-quickest, setting the Aussies up for a red-hot chance of multiple medals in the final, but it wasn't to be.
Sisters have never claimed gold and silver medals in the same event at an Olympic Games, let alone in swimming.