Flyhalf Bernard Foley kicked a controversial 80th minute penalty to give the Wallabies the win against a brave Scotland side who refused to wilt in the face of five Australian tries before sensationally hitting the front in the dying stages.
Victory brought a sense of relief for coach Michael Cheika, and a semi-final meeting with Argentina next Sunday, but also much to ponder from a game in which Australia were at times their own worst enemy.
They allowed Scotland a try from a ruck when their close-in defenders stood statuesque as Peter Horne skipped past them, before their opponents profited from a charge-down of Foley’s kick and finally an intercept for a hat-trick of soft tries.
"There were some poor decisions made by us out there," Cheika told reporters after the game. "Our defence was also not up to standard. But after scoring five tries in a quarter final you expect to go through."
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Cheika asked his team to play an open style of rugby and to attack Scotland with ball in hand. He admits it was a gamble that almost backfired.
"Maybe that was naive of me to open it up for them, maybe we should have played more of a kicking game," he said.
The Wallabies were also penalised on five occasions at the scrum, with Scotland turning three of those into points, a reversal in fortunes at the set-piece which had been solid in the tournament to date.
Foley was sensational in Australia's pool victory over England earlier in the tournament, but made basic errors, as well as missing all three first-half conversion attempts, that had coach Cheika pondering replacing him at halftime.
But a desire to stick to the original game-plan and a gut feel he would come right meant the flyhalf known as the "ice man" stayed on the pitch to win the game the game for his side.
"We didn’t let it stress us, otherwise we would have changed him at halftime. We know he is a great kicker.
"You have to hold your nerve. You can't panic every time something goes against you."
Wallaby Drew Mitchell was a stand-out performer and scored two tries that moved him to 14 in all World Cups, one behind New Zealand's Jonah Lomu and Springbok Bryan Habana.
The Toulon wing, along with Matt Giteau, has been the beneficiary of a recently-introduced rule in Australia that says overseas-based players could be selected for the national side if they have played 60 or more caps for the side.
(Editing by Mitch Phillips)
