The 20-year-old Scott timed his surge to perfection in the blue riband 100m freestyle. After turning for home in sixth place, he then overpowered South Africa's Chad le Clos and Chalmers to touch in 48.02 seconds, instantly deflating the roaring crowd.
"I had to stick to what I'm good at, and that's bringing it home," Scott said. "I'm very pleased with how I executed."
It was Scott's fourth medal at the Gold Coast Aquatics Centre but first gold and his victory sets up a fascinating battleground in the 100m freestyle for the next two years before the Tokyo Olympics involving Chalmers and American Caeleb Dressel.
GREAT SCOTT! 🏴 Duncan Scott wins gold in the 100m Freestyle. 🇦🇺 Kyle Chalmers wins silver in a dead heat with 🇿🇦 @chadleclos. #GC2018 #7CommGames pic.twitter.com/glpsoUGht6 — 7CommGames (@7CommGames) April 8, 2018
While Scott's victory was greeted with muted shock, the home fans at the pool managed to find their throat again when Mitch Larkin led home a clean sweep of the men's 50m backstroke.
THE BACKSTROKE BOYS! 🇦🇺 🇦🇺 🇦🇺 It's an Aussie trifecta with @Larkin_mitch winning Gold, Ben Treffers Silver and Zac Incerti Bronze. 💪👏🔥#GC2018 @maccas pic.twitter.com/dPy1KYkHAf — 7CommGames (@7CommGames) April 8, 2018
Larkin, who also won the 100m title, touched in 24.68 seconds with Ben Treffers second and Zac Incerti taking the bronze.
"I knew if all things went to plan we could go one, two, three," Larkin said. "The crowd is awesome, I knew it would be loud tonight with the three Aussies here. It's awesome."
The crowd had barely calmed down from the backstroke when Cate Campbell overcame a slow start to win the women's 50m butterfly, pipping Holly Barratt and Madeline Groves and giving the hosts a second sweep within 10 minutes.
"When we got one, two, three... I swear if there was a roof on this stadium it would have been lifted off," Campbell said.
Another Aussie sweep in the women's 50m Butterfly! 🇦🇺 🇦🇺 🇦🇺 @catecamp wins Gold, Holly Barratt Silver and @MaddieGroves_ Bronze. 💪👏🔥#GC2018 #7CommGames pic.twitter.com/i5JTmYVt9C — 7CommGames (@7CommGames) April 8, 2018
Chalmers made up for his dead-heat for silver in the 100m when he helped the Australians to victory in the 4x200m freestyle relay in a Commonwealth Games record of seven minutes, 5.97 second.
England finished second, with Scotland in third.
The loudest cheer, however, was reserved when Gibraltar, who had not completed 700 metres when the Australians won, finished about 70 seconds later.
The 5th Gold medal of the night for Australia! Super Sunday capped off with the Aussie men dominating the 4x200m freestyle relay with a new GR. #GC2018 #7CommGames pic.twitter.com/NPw5I6dDSg — 7CommGames (@7CommGames) April 8, 2018
MASSE DOUBLE
Kylie Masse had earlier led home a Canadian one-two in the women's 200m backstroke with impressive teenage team mate Taylor Ruck picking up her fourth silver medal, and sixth overall, of the meeting.
Masse completed the 100m-200m double with her victory in 2:05.98, well ahead of the 17-year-old Ruck, who held off fast-finishing local hope Emily Seebohm.
"The 200 is quite a funky race," Masse said. "You have to get used to how you swim it, as in do you go out faster or conserve your energy.
"It's a bit of a game (so) ... I'm super happy with that. That wasn't my best time but it was close to it. I just tried to do an easy first 100 metres, then really build the 50 and put my all into coming home."
The defending champ does it again! 🏴 Siobhan Marie O'Connor wins the 200m Individual Medley. 🇦🇺 @BlairEvans finishes in 5th and 🇦🇺 Meg Bailey finished in 8th.#GC2018 #7CommGames pic.twitter.com/nkyQvmc6vn — 7CommGames (@7CommGames) April 8, 2018
England's Siobhan-Marie O'Connor also retained her 200m individual medley title with a comfortable victory over Canadian duo Sarah Darcel and Erika Seltenreich-Hodgson.
The Australians also won both para-swimming finals on Sunday with Jesse Aungles clinching the men's SM8 200m individual medley, while Lakeisha Patterson won the women's S9 100m freestyle.
The host nation now have 16 gold medals in their overall total of 45 at the pool, well ahead of second-placed England on 17, eight of which are gold.
