The United States are wary of a "formidable" Australia after the Opals staged a great escape to book a quarter-final showdown with their arch-rivals in the women's Olympic basketball tournament.
The all-conquering Americans remain on track for a seventh consecutive title after winning their three group games, but now face a team that inflicted a rare defeat on them prior to the start of the Games.
That Australian side featured its best player Liz Cambage, but she pulled out ahead of Tokyo citing mental health struggles and her team have struggled without her.
The world number two Opals suffered tough losses to Belgium and China in the preliminaries and were left with the unenviable task of needing to beat Puerto Rico in their final group game by at least 25 points to stay alive on Monday.
Stunningly they did, battling to a 96-69 victory despite being behind at the end of the first quarter.
"Was it the great escape? I guess so," skipper Jenna O'Hea said. "Knowing before the game that it was a 25-point margin (required to qualify), it's a bit daunting in the back of your mind. It wasn't a small number at that."
It ensured a clash on Wednesday with the world's top-ranked team, led by WNBA legends Sue Bird, Diana Taurasi and Sylvia Fowles and who are on a 52-game winning streak in Olympic competition.
"Australia will be a formidable opponent because we know each other so well, and we look forward to the challenge of getting out of the quarter-finals," said US coach Dawn Staley.
"We certainly have to execute on both sides of the ball and continue to get better to advance."
Two teams from Asia made it to the quarter-finals for the first time with undefeated China, spurred by outstanding centre Li Yueru, facing Serbia on Wednesday with a semi-final berth at stake against either the US or Australia.
Hosts Japan made the last eight for the second straight time and will meet Belgium, with Japan's American coach Tom Hovasse insisting his side have the goods to win gold.
"I know there are people outside of our team that are doubters," he said.
"But when I took this job five years ago, I said at the first press conference that I want to win the gold medal and that I want to play the USA in the title game."
In the other quarter-final, fifth-ranked France take on world number three Spain.