Swim queens have struck gold again as a high-profile batch of Australian women make heartening starts in their Olympic medal quests.
Australia's team in Tokyo features a highest-ever percentage of women - 53.5 per cent - and they largely delivered on Sunday, despite the crash of Ash Barty.
The women's 4x100m freestyle relay team - sisters Cate and Bronte Campbell, Emma McKeon and Meg Harris - set a world record to win Australia's first gold of the Tokyo Games.
Cate Campbell joins swim legend Dawn Fraser and eight-time equestrian Olympian Andrew Hoy as Australians to win gold in the same event at three consecutive Olympics.
And Campbell is only the third to win gold after being Australia's opening ceremony flagbearer, joining rower Bobby Pearce (1928) and Hoy (1996).
"This is the third Olympics in a row that Australia has won this event and that in itself needs to be celebrated," Campbell said.
"To do that for 12 years in a row is incredible."
Jack McLoughlin (silver, 400m freestyle) and Brendon Smith (bronze, 400m individual medley) also won medals on Sunday.
But Australia's world No.1 tennis star Barty logged 55 unforced errrors in her first-round singles loss to Spain's world No.48 Sara Sorribes Tormo, 6-4 6-3, just 15 days after winning the Wimbledon title.
Barty's demise - she's still alive in doubles with Storm Sanders - came as highly-touted Australians Stephanie Gilmore and Sally Fitzgibbons advanced through opening heats in surfing's Olympic debut.
Canoeist Jess Fox began her quest for an elusive Olympic gold with a strong showing in the first heats in the women's K1 slalom.
World No.1 Fox, who took silver in 2012 and bronze four years later in Rio, was second-quickest, ensuring a semi-final slot.
Also Sunday, Australia's women's quadruple sculls - Ria Thompson, Rowena Meredith, Harriet Hudson and Caitlin Cronin - produced a heartening repechage win to advance into their final.
Australia's women's beach volleyballers Mariafe Artacho del Solar and Taliqua Clancy notched a confidence-boosting straight-sets opening victory.
The Hockeyroos opened their campaign with a clinical 3-1 win over Spain as Olympic debutant Rosie Malone scored and set up another.
And Australia's softballers almost upset powerhouses the United States, who prevailed 2-1.
The softballers, fourth in standings with a 1-3 record, must defeat Mexico in Monday's final group game to reach the bronze medal playoff.
