Success for Cate Campbell at July's world titles is hard to predict according to her coach Simon Cusack, despite her scorching national swimming championship form in Adelaide.
Then again, it is understandable why Cusack is not one for bold calls.
Campbell, 20, fired a warning shot to Olympic champion Ranomi Kromowidjojo ahead of the world titles in Barcelona with a national 100m freestyle win in 52.92 seconds, the second-fastest time of the year.
It came a day after Campbell set 2013's fastest (52.83) in the semis - a time that would have won London Olympic gold.
She finished ahead of her younger sister Bronte Campbell (53.85) ensuring they were both on the plane to Spain and that their London Olympic sister act was no fluke.
But instead of talking up Cate Campbell's chances in Spain, Cusack simply wanted his young charge to arrive in one piece.
"We are seeing now what we should have seen in London," Cusack lamented.
"One thing I have learned coaching Cate for 11 years is that you never count your chickens.
"She is supremely talented but she has been let down by bad luck with health."
Cate Campbell joked that she would have to be stored in bubble wrap ahead of the world titles.
No wonder - Campbell was struck down by career-threatening post-viral fatigue syndrome after claiming Beijing Olympic 50m freestyle bronze at the age of 16.
When all looked lost, Cusack turned to a Chinese herbalist.
"I was clutching at straws by this stage. I would have jumped on one foot and juggled (if it helped)," Cusack said on Wednesday.
"But it (herbalist) worked. We gradually rebuilt her."
All signs pointed to a triumphant Olympic return at London.
This time a fully recovered Campbell was armed with Bronte after they made history by becoming swimming's first Australian sibling Olympians in 40 years.
But even their special chemistry could not avert another disaster.
After revealing Bronte secretly carried a torn calf into the Games, Cusack said the younger sister was then reduced to nurse duties as her Olympic roommate Cate was struck down at London with an inflamed pancreas.
Cusack said Cate Campbell complained she had "glass in her stomach" before the 4x100m freestyle relay at London - but remarkably still went out and helped Australia claim gold.
"She went downhill from there," Cusack said.
"And (Bronte) was rooming with Cate, holding her head out of the vomit.
"In London they were a two-for-one package. They were either going to go very well or they were going to feel each other's pain which unfortunately they ended up doing."
Now the sisters loom as a dangerous world titles double in the 100m freestyle.
Cate Campbell hailed her coach as the light that helped lead her out of the dark times.
But Cusack wasn't so sure.
"It was just unfinished business," he said.
Asked about the key to their special bond, Cusack said: "I have never bull*****ed her, basically".
Meanwhile, dual Olympian Sally Foster clocked 2:23.94 - the year's third-fastest and second on the Australian all-time list - to win her third 200m breaststroke title.
London Olympian Matson Lawson (1:56.59 PB) won the 200m backstroke final and Buster Sykes (2:13.25) the men's 200m breaststroke title.
In semi-final results, Matt Targett was fastest qualifier for Thursday night's 50m freestyle final (21.92), Alicia Coutts (26.17) for the women's 50m butterfly, Chris Wright (51.77) for the men's 100m butterfly and Belinda Hocking (2:08.58) in the women's 200m backstroke.