Emily Seebohm has missed out on selection for next month’s world swimming titles in South Korea.

Seebohm squandered her final chance for selection when she finished third in her pet event – the 200m backstroke – behind teenagers Kylee McKeown and Minna Atherton on Friday’s last night of the six-day trials in Brisbane.

The 13-year team veteran had been aiming to make an unprecedented seventh world titles team and become the first woman to win three-straight 200m backstroke world titles.

However, Seebohm, 27, was left to wonder what might have been after McKeown won the 200m backstroke final in two minutes, 30.65 seconds.

Seebohm finished more than two seconds behind 17-year-old McKeown in the final and almost three seconds shy of her Commonwealth record.

The top two in each final earn selection, providing they also finish under the nominated qualifying time.

“It does surprise you … she’s been there (national team) for a decade,” Dolphins head coach Jacco Verhaeren said of Seebohm.

Seebohm opted not to speak to reporters after the final, but revealed earlier this week her preparation had been affected by illness.

The winner of 53 international medals was sweating on selection on the final day after finishing a distant fourth in her other event, Monday’s 100m backstroke final, won by 19-year-old Atherton.

There was better news for Rio 400m freestyle champ Mack Horton was breathing a sigh of relief after receiving the nod for the 27-strong squad for the July 12-28 world titles in Gwangju, despite technically failing to meet SA’s qualification.

Mack Horton got a lifeline. Photo: Getty

Horton suffered a shock 400m freestyle loss to Jack McLoughlin, finished fifth in the 200m and second in the 800m outside the qualifying time.

Yet Dolphins mentor Verhaeren used his discretionary powers to pick Horton. He is set to contest the 400m freestyle and 4x200m freestyle relay in South Korea.

“Obviously, he is disappointed … but he is an Olympic champion. It’s not panic situations. He could turn it around in weeks,” Verhaeren said.

While Seebohm missed out, former world champion Bronte Campbell snapped up her final selection chance.

She clocked 24.17 seconds to finish second just 0.12 behind her sister – former world champion Cate – in Friday’s 50m freestyle final.

Campbell had to rely on the 50m for individual selection after she clocked a qualifying time in Thursday’s 100m freestyle final but missed selection because she finished third.

It marked the first time in six years Campbell had missed an individual 100m spot.

Bronte Campbell also looks likely to feature in the 4x100m freestyle relay team,  the world record holders.

It capped a remarkable comeback for Campbell who underwent 2018 shoulder surgery and endured illness at April’s national titles.

And, Thomas Fraser-Holmes was the feel good story after winning Friday’s 400m individual medley final to book a world titles spot.

He is on the comeback trail after being suspended for 12 months for missing three drug tests in a year.

-AAP