By Mark Trevelyan
RIO DE JANEIRO (Reuters) - Pernille Blume of Denmark set the fastest time in the heats of the women's 50 metres freestyle in Rio Friday, and Australian sisters Bronte and Cate Campbell qualified comfortably after missing out on medals in the 100 metres the night before.
Blume swam 24.23 seconds in the same heat as Bronte to go through in first place to the evening semi-finals, with Britain's Fran Halsall second fastest and Aliaksandra Herasimenia of Belarus third.
Of the 16 to go through to the semis, Bronte Campbell was fourth fastest, Cate seventh, and defending champion Ranomi Kromowidjojo of the Netherlands was equal eighth along with Canada's Chantal Van Landeghem.
"It was rough backing up after last night, which wasn't my best night of the week so far but it's great to go out there and have a good race this morning," Bronte Campbell said.
She finished fourth, and Cate sixth, in Thursday's 100m final, won in a dead heat by Simone Manuel of the United States and Canada's Penny Oleksiak.
Manuel came 11th in the 50m heats and the Netherlands' Inge Dekker, who underwent treatment earlier this year for cervical cancer, was equal 13th.
Chinese swimmer Chen Xinyi was a no-show, after Chinese state media said she failed a dope test at the Games.
The Xinhua news agency, citing the country's swimming association (CSA), said she tested positive for a banned substance on Aug. 7 in the latest doping scandal to mar competition at the Games. Chen was listed on the official start sheets on Friday as the heats got under way and then recorded on the results as DNS (did not start).