Ash Barty's quest for Tokyo gold has started impressively while John Millman beat rising Italian talent Lorenzo Musetti 6-3 6-4 to progress to the second round of the Olympic men's tennis event.
Teenager Musetti had led Novak Djokovic two sets to love in the French Open round of 16 before eventually retiring hurt in the fifth set and was fancied to topple Millman on the Ariake Tennis Park hard court on Saturday.
But the form line didn't account for the Brisbane workhorse's tremendous resolve, particularly while wearing Australian colours in his second Games appearance.
He broke Musetti for a 5-3 lead and then served out the first set, before twice losing his serve after gaining breaks in the second.
Millman held his nerve to win a tight service game at 3-4 before Musetti's frustrations eventually got the better of him in a 96-minute contest played in hot, humid conditions.
Millman recorded the Games' first 6-0 6-0 win to open his account in Rio five years ago, before blowing leads in both sets against eventual bronze medallist Kei Nishikori in the second round.
Established as a top-50 player since then, Millman is leading the Australian men's charge after the withdrawal of Nick Kyrgios and Alex de Minaur.
His second-round opponent is the in-form Alejandro Davidovich Fokina, with world No.1 Djokovic a likely third-round opponent.
Later in the day Barty paired with Storm Sanders for a 6-1 6-2 win against Japan's Makoto Ninomiya and Nao Hibino, the sixth seeds sending a warning shot in their 50-minute procession.
World No.1 Barty, fresh off her Wimbledon triumph, begins her singles campaign against Spain's Sara Sorribes Tormo on Sunday while Ajla Tomljanovic is also in action.
Samantha Stosur, in an Australian tennis record fifth Games appearance, was comprehensively beaten 6-4 6-2 by Elena Rybakina.
Her focus will now switch to the doubles alongside Ellen Perez.