The 19-year-old McKeown broke her own Commonwealth and Australian records in the 200m backstroke on Friday.

McKeown's time of two minutes 04.31 seconds is the quickest in the world in the event in the past 18 months.

And McKeon has recorded the fastest 100m freestyle time this year to notch another victory over Cate Campbell.

McKeon triumphed at the Sydney Olympic Park Aquatic Centre Open in 52.29s, bettering this year's previous world-best mark of 52.43s set by Campbell at last month's national titles.

Campbell set that time in a heat at the nationals, with McKeon beating her in the final.

And McKeon repeated that feat on Friday with a sizzling personal best to eclipse Campbell (53.27s) and Madison Wilson (53.78s).

"I've just got a lot stronger and done a lot of work in the gym, that's where I think I've made big gains," McKeon said.

"And every time I get to race Cate and be up against the best in the world it adds to my confidence and it's just good race practice."

Meanwhile, McKeown's personal best in the 200m backstroke final came after she went hard in Thursday night's heat.

"I planned to come back this morning and see what we could do, so I'm pretty impressed that we were able back up some pretty good swims," McKeown said.

"I just trusted myself a bit more in the first 100m today to get out a little faster which did hurt a lot in the back-end.

"It's always our plan to put as much pressure on as we can at these meets to get the most race practice we can.

"It's nothing compared to (Olympic) trials and I'm expecting a lot more nerves there."

Australia's Olympic swimming trials will be held in Adelaide on June 12-17, where McKeown will take on stalwart Emily Seebohm, who placed second in Friday's final.

Reigning Olympic champion Kyle Chalmers prevailed in the men's 100m freestyle on Friday in 49.34s.

Australian Associated Press