Australia coach John Connolly admitted England's pack was the difference between the sides after his team's shock 12-10 World Cup exit.
Mortlock (left) and Connolly (right) ponder their World Cup exit
He also confirmed he would step down as coach now their World Cup bid was over.
"The scrum was destroyed and England controlled the breakdown. Their scrum is world-class, but the breakdown is an issue for the whole team," he said.
"I said before the tournament their scrum and line-out would be a massive threat to everyone."
Australian captain Stirling Mortlock said he was partly to blame for defeat, having had a disappointing day with his goal-kicking.
But he also said England were deserved winners and that, if they repeated the performance they gave in Marseille, they could be a match for anyone left in the tournament.
"It was an extremely quiet dressing room, and understandably so," said Mortlock. "A lot of credit must go to England, the way they attacked the breakdown and didn't allow us to get into rhythm.
If England can be as effective at the breakdown as they were today, then they can give anyone a shake
"I was disappointed a number of my kicks were extremely close. I should have kicked them, and it would have been a different game.
"If England can be as effective at the breakdown as they were today, then they can give anyone a shake."
Connolly is not the only Australian bowing out of international rugby. Veteran half-back pairing George Gregan and Stephen Larkham are also retiring.
Mortlock said the duo deserved something better to mark the end of their careers.
"Stephen and George have given so much to the world of rugby, and John, too," he said.
"For them to bow out in a quarter-final, everyone is extremely disappointed for them."