Stuart Lancaster's side were 54-12 victors over Fiji last weekend with George Sharples standing out, scoring two tries.
However, regular wing Chris Ashton is back from suspension leaving the coach with a tough decision over who out of the two to leave on the sidelines at Twickenham.
"The guys are on top of their games and to be honest it's about making sure what is the best team for us to beat Australia this weekend," Catt told Sky Sports News.
"If that means changing it, we will, if it doesn't, we won't.
"Certain guys put their hands up at the weekend and performed well so there is no reason why we should change it.
"He (Ashton) doesn't have to come in.
"He's got a lot of credit for the way he has played. Hopefully he has learnt his lesson and won't do the things he has done which put him in a spot in the first place.
"We have a very important training session this afternoon and if he comes through that and plays well with the attitude we know he can have,
he is definitely in with a shout."
England face an Australian side fresh from a humiliating 33-6 defeat to France last weekend.
The visitors will be without flanker David Pocock because of a calf injury, while lock Kane Douglas is out with a knee problem.
However Catt, who has been watching plenty of tape of the Wallabies, is wary of playing a side who have in the past come back when the odds were against them.
"They have not just suffered a heavy defeat," he said. "They have taken New Zealand to a draw and beaten Argentina.
"We all know what a capable side they are. We are under no illusions, they will bring their A-game on the weekend.
"They will park the disappointment just like they have done in the past.
"If they come on a northern hemisphere tour and they beat England they will say that it has been a successful tour."
"(Michael) Hooper now is doing everything for Australia. He is on the good breakdown and good on his feet, but yes, the leadership of Pocock makes a difference."
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