BRISBANE (AFP) - Olympic champion Mack Horton was ruled out of the individual races at next month's world championships when he finished third in the 800 metres at the Australian trials on Tuesday (June 11).
Emma McKeon, Australia's most successful swimmer at the Rio Olympics, held off rising star Ariarne Titmus to book her spot in the 200m freestyle next month in South Korea.
But Horton, who had already missed out in his pet 400m event, and the 200m, completed an unwanted treble when he was beaten in the 800m, clocking 8min 1.30sec.
The 23-year-old, who beat China's Sun Yang for gold in the 400m at Rio, came third in the 800m behind Jack McLoughlin, who touched in 7:46.79, a new personal best.
Only the top two in each final earn selection for individual races at the world championships, and only if they swim under the designated qualifying time.
Joshua Parrish (7:54.94) did not make the grade alongside McLoughlin, who also edged out Horton in the 400m on Sunday.
The strapping 24-year-old announced himself last year, claiming 1,500m gold at the Commonwealth Games before upsetting a top field to win the 400m and 800m at the PanPacs in Tokyo.
"That was all right, I kind of wanted to go faster," he said of his 800m time. "But I'm pretty happy with how it is going so far."
He swims the 1,500m on the penultimate day of the trials on Thursday.
McKeon, who shared silver with American superstar Katie Ledecky behind Italian great Federica Pellegrini at the last worlds in Budapest, came out of the blocks first and never looked back, hitting the wall in a personal best 1:54.55.
It was fractionally outside the Commonwealth record set by teenager Titmus last year, setting the pair up as serious challengers for gold next month.
"I haven't done a PB in that race for quite some time, I think I lost a bit of confidence for a bit," said McKeon, who collected a gold, two silvers and a bronze at the 2016 Rio Games.
"I'm usually out pretty fast... I just focus on my stroke count and timing."
McKeon has also qualified for the 100m butterfly, while Titmus fired a warning shot to Ledecky with a new Commonwealth record in the 400m freestyle this week.
In other racing on Tuesday, David Morgan qualified in the 200m butterfly.