Gold Coast - Olympic champion Adam Peaty flexed his muscles in the Commonwealth Games 100 metres breaststroke on Friday as the title-holder clocked the best time of the morning heats.
South Africa's Chad le Clos continued his bid to rewrite Games history, meanwhile, as he went out hard in the 200m freestyle heats before he lines up in the evening's 50m butterfly final.
Peaty, leading England's challenge against home nation Australia's dazzling swimming cast, is unbeaten in the 100m breaststroke since storming to gold in Glasgow four years ago, and touched in 59.14 seconds in the Gold Coast sunshine.
Aussie Matt Wilson finished a distant second in 1:00.29 but realistically Peaty's rivals will be contesting silver, such is the gulf in class between them and the 23-year-old world record-holder.
"It was slower than expected but that's sport - you never know what you're going to get," said Peaty. "A true margin of what I'm capable of will come tonight, and hopefully tomorrow night."
Fellow Englishman James Wilby, who won 200m gold on Thursday, was the only other man to break the one-minute mark as he pipped South Africa's former Olympic champion Cameron van der Burgh to win his heat in 59.80.
History-chasing Le Clos is six Commonwealth Games medals behind shooters Mick Gault and Philip Adams, who lead the way with 18.
He went out strong in the 200m freestyle heats - one of seven events the South African is contesting on the Gold Coast - but he was caught by Australia's Kyle Chalmers, who clocked 1:47.10 to win by just under half-a-second.
Le Clos timed 1:47.37 - which qualified him for the final in
"I thought I'd be a little quicker," shrugged Le Clos, who claimed a surprise silver medal in the 200m free at the 2016 Rio Olympics.
Olympic 100m champ Chalmers said: "I knew he was going to be out quick. I just wanted to get on the wall first."
Mack Horton also returned to the pool the morning after adding the Commonwealth crown to his 400m Olympic title, finishing second to England's James Guy, who won their heat in 1:47.04.
Scotland's Duncan Scott clocked the fastest time of the 200m prelims in 1:46.62.
Australia dominated the 50m freestyle heats as Cate Campbell followed her phenomenal anchor leg in Thursday's 4x100m world record to top the timesheets in 24.24 seconds, almost half-a-second quicker than Shayna Jack with sister Bronte Campbell third quickest.
"It was a bit exciting last night," said Cate. "We were all up late so that was nice, everyone sat down and unwound and didn't go to bed all hyped up."
World record-holder Kylie Masse posted a new Games mark of 58.70 as the Canadian qualified in top spot for the women's 100m backstroke, while Australian Clyde Lewis went quickest in the men's 400m individual medley with a 4:17.25.