Australian swim star Cate Campbell says she only helped set a new Olympic record to avoid training.
Campbell and her fellow 4x100m freestyle relayers emphatically underlined their gold-medal favouritism at the Rio Games with a stunning swim in the heats on Saturday.
With sisters Cate and Bronte Campbell opening their Rio campaigns, the Australians clocked 3 minutes 32.39 seconds to be quickest qualifiers for Saturday night's final.
Following Madi Wilson and Brittany Elmslie into the water, Bronte and then Cate helped eclipse the previous Olympic mark of 3:33.15 set by Australia when winning gold at the London Games four years ago.
But Cate says she had ulterior motives for deciding to race in the heat, rather than save herself for Saturday night's final.
"I decided to have a hit-out, otherwise I would have to come in and do a training session and it's madness in that warm-up pool," she said.
And her sibling Bronte issued an ominous warning: they have plenty in reserve.
"We were put in a good position so Cate and I could have a bit of a blow out without giving it everything," Bronte said.
Earlier in the opening swimming session of Rio's Olympics, fellow Australian 400m freestyler Mack Horton lit the fuse in his ongoing rivalry with China's Sun Yang.
Horton qualified second fastest for Saturday night's final after a heat swim against a field also featuring China's Sun Yang, who served a doping suspension in 2014.
The pair had a flashpoint at the training pool earlier in the week when world champion Sun, who also advanced to the final, tried to distract the Australian Olympic debutant.
"He splashed me to say hi and I ignored him. I don't have time or respect for drug cheats," Horton said.
Horton's comments came after compatriots Thomas Fraser-Holmes (400m individual medley), Emma McKeon (100m butterfly) and Jake Packard (100m breaststroke) advanced in their respective events.
Fraser-Holmes will race in Saturday night's final while McKeon and Packard will contest semi-finals on the same night.
Australians who didn't progress in their events after Saturday's heats were Travis Mahoney (400m medley), Keryn McMaster and Blair Evans in the women's 400m medley, Madeline Groves (100m butterfly) and Joshua Palmer (100m breaststroke).