[1] Netherlands' Ranomi Kromowidjojo smashed a new Olympic record to strike a fourth sprint freestyle double in history, since East German Kristin Otto did so in 1988, her fellow countrywoman Inge de Bruijn in 2000, and Germany's defending champion Britta Steffen in 2008.

She blistered the field with a sterling time and a textile best in 24.05 to slice off Steffen's previous Olympic record by a hundredth of a second (0.01).

[6] Meanwhile, Sweden's Therese Alshammar shook off a pinched nerve injury to officially compete in her fifth Olympics, but managed only to claim a sixth spot in 24.61.

[5][7] Notable swimmers missed the top-eight final including Aussie sisters Bronte and Cate Campbell, defending bronze medalist; and Halsall's teammate Amy Smith, who finished outside the roster by 16-hundredths of a second with a ninth-place time in 24.87.

[8][9] Earlier on the morning prelims, Smith picked up a sixteenth spot in a most exciting three-way swim-off against U.S. sprinter Kara Lynn Joyce and Iceland's Sarah Blake Bateman after they each posted a matching time of 25.28.