Katie Ledecky has led the USA to gold in the women's 4x200m freestyle, while Australia's Kyle Chalmers stole the headlines in the men's 100m freestyle.
The 19-year-old Ledecky swam the final leg as the United States took gold in the final event of another exciting night of swimming at the Rio Olympics. Australia came home in second, with Canada taking bronze.
It was Michelle Coleman of Sweden who set the early pace ahead of the Americans, but the race quickly became a two-team event when Emma McKeon swum the Australians into contention over the second leg and touched first at the halfway mark.
Bronte Barratt, swimming her final race before retirement, kept the Australians just in front of the United States in the third leg, but with the great Ledecky swimming last for the United States no lead would ever have been enough, and while Tamsin Cook swam valiantly, there was no stopping Ledecky.
Earlier in the night, Australia did get one over the United States, with Greg Chalmers a surprise winner in the men's 100m freestyle in a time of 47.58 seconds.
Defending Olympic champion Nathan Adrian had only just scraped his way into the semi-finals after a slow heat, but the American and Australia's Cameron McEvoy were the favourites heading into the race.
It was Santo Condorelli of Canada who turned first after the opening 50m, with Adrian second and Caeleb Dressel of the United States third. Adrian then began to power ahead with McEvoy also coming to the fore.
However, it was Chalmers who pulled off a spectacular finish to take gold. Having turned in seventh, the 18-year-old surged through in the final 25m to edge out his more fancied rivals.
Adrian was forced to settle for bronze, with Belgium's Pieter Timmers sneaking second.
Mireia Belmonte of Spain was the victor in the women's 200m butterfly in a time of 2:04.85, edging Australia's Madeline Groves by three hundredths of a second.
It was Groves who started strongest, turning after the first hundred in front in what was a personal best time, but Belmonte slowly ate into her advantage before moving ahead by 0.14 as they turned for the last 50m.
The Spaniard held on to win by the smallest of margins, with Groves second and Natsumi Hoshi of Japan in third.
In the day's first final, Dmitriy Balandin secured Kazakhstan's first gold with victory in the men's 200m breaststroke in a time of 2:07.46. Josh Prenot of the United States took silver, with Anton Chupkov of Russia.
Yasuhiro Koseki led the way for the majority of the race, with Balandin moving into second behind the Japanese swimmer with 100m to go. However, Koseki faded terribly over the last 50m and it was Balandin, swimming out in lane eight, who touched first in a highly competitive finish.
One could have put a blanket over the swimmers at the end, with the winning time 2:07.46, and Kevin Cordes in last touching at 2.08.34.