Opals coach Sandy Brondello has lamented her team's limited Olympic build-up, but not the late withdrawal of star Liz Cambage after they faded badly in a 85-70 women's basketball loss to Belgium.
Australia led by seven in the third term and one at the last break of their tournament opener before Belgium, in their first Olympic appearance, dominated a 29-13 final term.
Ezi Magbegor (20 points, eight rebounds), Cayla George (12 points, 10 rebounds, four assists) and Katie Ebzery (11 points, nine rebounds, six assists) had the Opals humming before WNBA star Emma Meesseman (32 points, nine rebounds, five assists) took over.
The result comes after key player, WNBA All-Star centre Cambage's withdrawal from the campaign citing mental health concerns shortly before they flew to Japan.
The Opals beat gold medal favourites the United States in a practice match immediately after her exit though, fuelling hope of a breakthrough Olympic title for the No.2 ranked side.
"No, we just haven't spent much time together," Brondello said when asked if Cambage's late exit had hurt them.
"We've had two games since February 2020; I think that was the problem.
"But we live in a COVID world and Australia has lockdown rules; it's unfortunate but no excuse ... we know we can play better."
Olympic rookies Belgium were no pushovers, fresh off bronze in June's FIBA EuroBasket to arrive match-hardened.
"It's amazing because this is part of our history right now, and if you would tell me before that we would beat Australia, one of the favourites, with 15 points? I would probably laugh," Meesseman said.
"But at the same time, I know every team ... we play and every team is beatable."
Brondello was critical of 14 turnovers, as well as unforgivable in-bounding mistakes and a general lack of sharpness at both ends.
"We weren't crisp, our screening wasn't good, we got a little fatigued," she said.
"That fourth quarter may come back to haunt us.
"Ezi played a really good game and she's going to get better and better.
"But she's 21, first Olympics. She's pretty crafty, but the most important thing is to not put too much pressure on her."
The Opals next face China on Friday before a final pool game against Puerto Rico, with the top two sides from each pool and the best two third-placed sides progressing to the quarter-finals.
Steph Talbot missed the game with a foot injury but Brondello was hopeful she'll be fit to play China.