Captain Ricky Ponting believes Australia are not the finished article yet.
Symonds played a match-winning knock under difficult conditions
He said there was still room for improvement, despite making their third World Cup final in succession.
They have now gone 16 games unbeaten in World Cup matches, after downing Sri Lanka by 48 runs (Duckworth/Lewis method) in the semi-final on Tuesday.
But Ponting said the team was not taking anything for granted in Sunday's final, which will be against India or Kenya.
Ponting said: "We are going okay but there is still a bit of improving to go yet, particularly on the batting side of things.
I don't know what is happening - I'm starting to grow a brain or something
"We are not that far away. Most of the batters are getting starts. They are just not going on with it.
"Let's hope it all clicks in the final."
Ponting reserved special praise for all-rounder Andrew Symonds, who smashed an unbeaten 91.
He came to the crease with Australia on 51-3 and shared a 93-run stand with Darren Lehmann to put Australia in a commanding position.
Ponting said: "Symonds played beautifully, like he has done throughout this tournament.
"His first game, he scored one of the best one-day hundreds you will see and today was the reverse of that, a very sensible innings."
Ponting was also delighted with Brett Lee's impressive bowling, clinching three wickets for 35 runs.
He said: "The way Brett's bowling is outstanding. Let's hope he's got one more good game in him."
Symonds joked about his thoughtful knock and said he was looking forward to Sunday's final in Johannesburg.
He said: "I don't know what is happening. I'm starting to grow a brain or something."