Vice-captain Brad Haddin says the lion-hearted fast bowler has nothing to prove and is "ready to go" for Wednesday's first Test at Trent Bridge.
That is despite some underwhelming performances on the Australia A tour and in Australia's opening warm-up match against Somerset.
Siddle and young firebrands James Pattinson and Mitchell Starc completed a ferocious net session at Trent Bridge on Sunday and are strongly tipped to form the fast bowling attack for the first Test.
Siddle is the only Australian bowler in the top 10 Test rankings, while England have James Anderson, Graeme Swann and Stuart Broad all up there.
Haddin said there was a good reason why Siddle was ranked the fifth best in world cricket.
"I think his experience shows, his ranking in the world shows he is a very consistent performer at this level," Haddin said.
"Sometimes guys need to get some wickets and feel confident going into big games. But Siddle, he's proven himself over a long time now. He knows exactly where he's at.
"I wouldn't read too much into the actual stats.
"He knows what to do to get through and win Tests. He's a class act and has been for a long time.
"He cranked it up a bit today leading into the Test match. It was quite frightening with the three quicks in there."
Haddin said his first look at the Trent Bridge wicket suggested it might play a little different to usual, with not as much grass as he was expecting.
With hot and dry conditions forecast for the week, the hooping swing that's the norm in Nottingham may not eventuate.
If that's the case, Siddle is almost a must-pick because of his ability to bowl long spells and maintain pressure.
Leaving Siddle out could be interpreted as a slap in the face to a man who has been the glue of the attack over recent years.
Jackson Bird also has that ability to keep things controlled but has just two Test caps to his name.
Fellow hopeful Ryan Harris is a class act, but there's always worry about how his body will hold up.
Importantly, Siddle's the only fast bowler in the squad who has played a Test match in England and his Ashes experience could be vital.
England's 13-man squad for the first Test nearly doubles Australia's 18-man collective for Ashes matches played.
Haddin, who is on his third Test tour of England, says he'll encourage his younger teammates to enjoy what they're doing despite the associated pressure.
Captain Michael Clarke is the only Australian to have played in a winning Ashes campaign, and Haddin desperately wants to know what it's like to sit in a triumphant shed after enduring some painful defeats including on the last Ashes tour.
"You can't get rid of (the losses), no matter what you try to do. Sitting in The Oval losing the Ashes, it hurts," he said.
"It will hurt forever I think. So I'd love to win this one to take a little bit of that hurt away."