Campbell realised a childhood dream when she booked a 100m freestyle Rio spot with her sister Bronte, ensuring they will be relay teammates on the Olympic stage for the first time.

Cate Campbell clocked a world class 52.38 – just shy of her 52.33 PB – to win the 100m freestyle final and relegate reigning world champion Bronte (52.38) to silver.

Cate Campbell was on track to eclipse German Britta Steffen’s 52.07 world mark set in the 2009 supersuit era but faded in the final 15 metres.

But nothing could wipe the smile off her face.

The sisters react after the swim. Photo: Dave Hunt, AAP.

The one-two finish not only locked in individual 100m berths for the siblings but also a 4x100m freestyle relay nod for Rio.

Bronte Campbell only qualified for the 50m freestyle at her first Games at London in 2012.

Cate Campbell contested both the 100m and 50m events at London.

“It’s so special, to be able to compete in a relay with Bronte that was always our dream,” Cate Campbell said.

“It’s the only time we can compete together and not against each other.”

It marks the third Olympics for Cate Campbell, the 2013 world 100m champion.

They became the first siblings to make Australia’s Olympic swim team since 1972 when they qualified for the London team.

Cate Campbell overcame a wrist complaint while her sister was nursing a shoulder injury but both impressed in last night’s 100m final.

Off and racing. Photo: Dave Hunt, AAP.

Cate Campbell clocked the fastest time of the year and the quickest she has been since she won the 2013 world title.

Told she was in front of the world record red line on the scoreboard during the 100m final, Campbell groaned: “I am always in front of that red line until the last 15 metres.

“It’s something I have been thinking about and talking about the last three years… but tonight it was about getting that one-two finish [with Bronte].”

Meanwhile, Cameron McEvoy qualified fastest for tonight’s 50m freestyle final.

James Magnussen kept alive hopes of an individual Rio berth after his 100m disappointment by being third fastest in the 50m semi-finals last night.

McEvoy topped the 50m semi-finals with 22.12 seconds ahead of Matt Abood (22.24) and Magnussen (22.34).

A top-two finish in the final within the qualifying time will guarantee an individual Olympic nod for Rio.

Australia’s Rio swimming team is finalised on Thursday.

Meanwhile, world champion Mitch Larkin clocked the world’s fastest time of the year (one minute, 53.90 seconds) to claim 200m backstroke gold.

Runner-up Josh Beaver also made the Rio team cut.

Commonwealth Games champion Taylor McKeown clocked a personal best 2:21.45 to win the 200m breaststroke gold.

Daniel Tranter (1:58.72) defended his 200m individual medley title but not in Rio qualifying time.

-AAP