England head coach Stuart Lancaster insisted "we've still got lots to work on" despite his side beating Australia 26-17 at Twickenham.
England dominated at set-pieces and secured victory thanks to two tries from Ben Morgan and 16 points from the boot of the 21-year-old George Ford.
"We played intelligently, the boys executed the game-plan. The scrum and maul were excellent," said Lancaster.
"But that was the game today - you have to play rugby in different ways."
Asked to rate his squad's recent performances, Lancaster responded: "Could do better, but it was never as bad as people were making out.
"Against New Zealand and South Africa, our game management let us down. Today our game management was much better."
England's forwards coach Graham Rowntree told BBC Radio 5 live sports extra that victory over Australia was "desperately needed".
"It was vital, because at times our performance levels haven't been as high as they should have been this autumn.
"The best thing to restore belief is winning. We had very frank discussions after New Zealand and South Africa, but you always need to look forward.
"We've got a great young set of lads and today it was all about getting a win against a big nation."
England face Wales on 6 February in the Six Nations curtain-raiser, opponents who also feature in their World Cup group.
Australia are in the same pool and their captain, Mike Hooper, admitted Saturday's defeat was hard to stomach.
"We couldn't get any ascendancy," he said. "There's a long time before we come back together as a group, so this is a disappointing way to finish.
"We just couldn't finish for the majority of the game and that lead to our downfall."