Bronte Campbell of Australia upstaged sister Cate to clinch the women's 100 metres freestyle gold medal as South African Cameron Van der Burgh stunned reigning world champion Adam Peaty in the men's 50m breaststroke on a thrilling night of swimming finals at Gold Coast 2018.
Campbell emerged victorious from the family affair in one of the blue riband events on the women's programme in a Commonwealth Games record 52.27sec, breaking a mark previously held by her formidable sister.
Van der Burgh has often found himself playing second fiddle to Peaty, much in the same way Bronte has to Cate, but found a way to beat the Englishman tonight in a time of 26.58.
The defending champion's success was one of three South African triumphs tonight as perennial Commonwealth Games medallist Chad Le Clos topped the podium in the men's 100m butterfly and Tatjana Schoenmaker completed the 100m and 200m breaststroke double.
Mitch Larkin had earlier delighted the home crowd by sealing the 50m, 100m and 200m backstroke treble.
Familiar demons returned for Cate Campbell as she led going into the final stages.
The 25-year-old faded from first to sixth in the corresponding event at the 2016 Olympic Games in Rio de Janeiro, prompting her to take a lengthy break from the sport.
She has returned with a vengeance at these Games, winning three golds coming into the penultimate day, but was beaten by the better swimmer on the night.
Bronte produced a magnificent finish, fighting back from third at the split to secure the title and avenge the defeat she suffered to Cate in the 50m freestyle.
Cate was forced to settle for silver, while bronze went to rising Canadian star Taylor Ruck, handing her a seventh medal from her seven races.
The two Campbell sisters then joined together on the top step of the podium to belt out the Australian national anthem.
Van der Burgh got off to a rapid start and was able to hold off the challenge of Peaty, the reigning world and European champion in the 50m, all the way to the wall.
Peaty finished second in 26.62, edging out team-mate James Wilby.
Schoenmaker, considered an emerging talent and hot prospect for the future, then made it back-to-back golds for South Africa when she clinched victory in the women's 200m breaststroke.
The South African clocked 1:06.41 to overcome Canada's Kierra Smith and Australian Georgia Bohl, silver and bronze medallists respectively.
More glory was to come for the African nation as Le Clos defended his 100m butterfly crown to seal yet another major international medal.
The Games record fell by the wayside as the four-time Olympic medallist touched the wall in 50.65.
England's James Guy was second and Grant Irvine of Australia third.
Bronte Campbell was not the only athlete to spring a surprise tonight as Wales' Alys Thomas announced her arrival on the global stage in style, winning the women's 200m butterfly in a Games record of 2:05.45.
The 27-year-old, who only began competing at this level at last year's World Championships in Budapest, claimed her country's first swimming crown of the Games.
Silver went to Australia's Laura Taylor, who came home in front of compatriot Emma McKeon.
The session had started in commanding fashion for the host nation, who enjoyed clean sweeps in the opening two events of the night.
Larkin spearheaded the Australian charge in the 200m backstroke, clocking 1:56.10 to oust team-mates Bradley Woodward and Josh Beaver.
Ariarne Titmus was even more dominant in the women's 800m freestyle, cementing her status as a star of the future by obliterating the rest of the field before stopping the clock at 8:20.02.
The 17-year-old grew in stature as the race went on and proved far too strong for Jessica Ashwood, who took silver over seven seconds behind her team-mate.
Kiah Melverton completed the Australian monopoly of the event by claiming bronze.
New Zealand's sole winner of the night was Opening Ceremony flagbearer Sophie Pascoe as the nine-time Paralympic champion won the women's SB9 100m breaststroke final in 1:18.09.
Paige Leonhardt and Madeleine Scott of Australia finished with the minor medals.
Australia's Matthew Levy, a two-time Paralympic gold medallist, sealed the men's S7 50m freestyle honours in 28.60.
Christian Sadie of South Africa earned silver and bronze went to Singapore's Wei Soong Toh.