Facing a major threat to their Olympic women's basketball dynasty, the United States shut down 2.03m centre Liz Cambage in the second half and beat Australia 86-73 on Thursday to reach the gold medal game.
The four-time defending champion Americans stretched their Olympic win streak to 40 games and will try to claim a fifth gold medal in a row Saturday against unbeaten France, which downed Russia 81-64 in the other semi-final.
"It is a great thing that we have another opportunity to win gold," US guard Sue Bird said. "It's harder to get there than it is to play the gold medal game."
The Aussies made sure of that, giving the US Women's NBA stars their hardest fight by shooting 20-of-33 from the field in the first half, 61 percent, and having Cambage strike for 19 points as the Opals led 47-43 at half-time.
"We took Australia's best shot and we were only down four," Bird said. "We didn't hang our heads or feel deterred. We knew it was going to be tough.
"We knew if we just tightened up our defence they weren't going to make those shots in the second half."
Cambage didn't score a point in the second half, the passing lines to her cut off by speedy guards and physical defence from Tina Charles and Candace Parker denying her the inside position that made her unstoppable early.
"We went down fighting," Cambage said. "They went to zone and I think that shook us up a little bit. They came out fighting and upped their defence.
"Yeah, they shut me down. They started double-teaming, going after the ball a lot more. It's hard. They are the elite of the basketball world."
Diana Taurasi hit two 3-pointers in an 8-1 US run to open the third quarter, putting the Americans up 51-48, and the Aussies led 56-55 late in the third hen the US women took command.
US guard Lindsay Whalen scored six points in a row and Charles added the net four in a 26-10 run that put the Americans ahead 81-66 with 3:25 to go, Cambage rendered a mere spectator.
"We couldn't allow her to get position," Parker said. "In the second half, we made it a lot harder to go to Liz."
"We had to stop Cambage," Charles added. "We weren't making it hard for her. We weren't using our quickness. We tried to get aggressive on defence. We took it more personal."
The US women, who have not lost at the Olympics since the 1992 semi-finals, improved to 16-0 against Australia in Olympic and world championship play. They are 8-1 against Russia and 6-1 against France in the same events.
Aussie 1.96m veteran Lauren Jackson, the all-time Olympic scorer whose 14 points gave her a career record 550, also was unable to solve the US defenders.
"In the second half we weren't able to adjust. They were just able to capitalize on our errors," Jackson said. "We did our best. We battled. We definitely showed strides but America are absolutely the best team here.
"We can hold our heads up high. We played hard right until the last minute. It was just one of those games where they pulled it back. We played our hearts out. Now we have to regroup and try and win the bronze medal."
Australia lost to the US women in the 2000, 2004 and 2008 finals but faced the Americans a round earlier this year after losing a group game to France.
Charles scored 14 points and grabbed 10 rebounds to spark the US women while Diana Taurasi added 14 points and Bird contributed 13.