FIBA couldn't confirm if the 2.03-meter (6-foot-8) Cambage was the first woman to dunk in an Olympic game. Her older teammates, who jumped off the bench when they saw the move, couldn't remember another one.
"That's the first time I've seen it in the Olympics," said Australia forward Lauren Jackson, playing in her fourth Olympics. "Even in the WNBA, you see some girls do it, on a fast break but she had the zone around her, she had people around her. She made it look so easy.
"I wish I could do that."
Celine Dumerc made sure there wasn't another first.
Dumerc hit a 3-pointer with 0.2 seconds left in overtime to give France an 80-77 victory over Britain and deny the hosts their first victory in Olympic basketball.
Dumerc, who finished with 14 points, also sent the game into overtime by hitting a 3-pointer with 5.6 seconds remaining in regulation.
"I was in actually in trouble, I didn't even look at the line, I didn't know if I was outside for the 3. I thought maybe I should pass, maybe go for a shot inside but then I went a bit to the left and shot," Dumerc said of her game winner in OT.
The United States stayed on course for a fifth straight gold medal by cruising past the Czech Republic 88-61 in a repeat of their 2010 World Championship final.
Canada and Turkey booked places in the quarterfinals.
Kim Smith and Courtney Pilypaitis scored 14 points each to help Canada beat winless Brazil 79-73.
Canada (2-2 in Group A) was up by 13 early in the third quarter before Brazil started to rally behind Erika de Souza and Clarissa Santos.
A three-point play by Santos gave Brazil (0-4) a short-lived 56-55 advantage early in the fourth quarter, but Canada quickly regained the advantage.
Canada led 64-63 midway through the fourth quarter when Pilypaitis and Shona Thornburn hit consecutive 3-pointers to make it a seven-point game.
De Souza had 22 points and 12 rebounds for Brazil.
Captain Nevriye Yilmaz scored 16 points and Turkey also advanced from Group A by beating already qualified China 82-55.
Isil Alben nailed two 3-pointers as Turkey ended the first quarter with a 12-0 run to take a 26-13 lead.
Turkey stretched the run to 18-0 to seal the game and China never really challenged again.
American-born Quanitra Hollingsworth added 10 points and 11 rebounds for Turkey (3-1). Chen Nan had 19 points for China.
Cambage caught the ball at the top of the lane from teammate Kristi Harrower with 6:14 left in the third quarter, took one dribble and drove to the basket for the one-handed dunk.
Cambage said she never has dunked before in a game and rarely tries to in practice. Still, she was happy to provide what's sure to be a highlight of the tournament.
"It's good to finally do it and get everyone off my back about it," she said. "I was wide open and I felt it and just did it. It was an out of body experience. I wasn't thinking about it."
Australian coach Carrie Graf has encouraged her young star to dunk in warmups to gain more confidence. She was proud to see her do it in the flow of the game.
"To have someone dunk at the Olympics, and a rising star of the women's world game, is huge," Graf said. "It's one of the many things that will continue to put women's basketball on the map as a global game. That's what it does.
"It's a historic, iconic moment in women's sport."
The dunk in the middle of a 12-0 run that gave Australia (3-1) a 44-33 lead — its biggest of the game.
Cambage not only dunked, she also secured the victory with two free throws and finished with 17 points and 10 rebounds for Australia.
"Cambage posterizing people is good for women's basketball," said Becky Hammon, an American-born guard who plays for Russia. "Making plays like that, memorable moments, people aren't going to remember who won or lost that game.
"They'll remember that dunk."
Because it didn't happen on a breakaway and Cambage did it with such ease, there was not much reaction from the crowd.
But the Australian bench erupted after the play and Cambage had a big smile as she ran back on defence.
"I never do it, but everyone wants me to do it, it's the one thing I'm really shy about," Cambage said. "I'm usually not shy about anything but when it comes to dunking I'm a bit shy."
"It's a very big — a massive win — every win is a good win. If we drop another game we could end up third or fourth. I got my fingers crossed that Russia will beat France."
Earlier, Ana Lelas scored 23 points and Sandra Mandir added 18 to help Croatia beat Angola 75-56 for its first victory. The win kept alive Croatia's chances to advance to the quarterfinals.