He said the Wales team must concentrate on getting their own game right to put in a match winning display against the Eagles.
Holley was speaking at the Wales squad base in downtown Chicago and described the mood in the camp as confident after a focus on plenty of hard work in preparation.
He said: "It will be a very physical challenge for us on Saturday. It really is about us concentrating on our own game and getting that right.
"There were strong performances from some of the youngsters against Canada and that really does bode well for the future.
"Against Canada we lacked a little clinical edge in their 22 and in the contact area they made life difficult for us so there are a few things we are working on."
He said the Wales team must take confidence from their try scoring success against Canada and take that into Saturday's encounter.
The squad has been boosted by the arrival of the giant Dragons lock forward Luke Charteris who said he is looking forward to the opportunity presented by being back with his teammates.
He said: "I've got the rest of the week to train with the boys and acclimatise and I am delighted to be here."
The Wales prop John Yapp said he is relishing the challenge of developing his skills in the tighthead position after earning a start at number three last Saturday.
He said: "I'm a lot better than I was twelve months ago as a tighthead and I it is great to be learning these new skills at this stage of my career. There are a lot of differences in the two propping positions and many of those involve the technique required.
"You also get attacked a lot more as a tighthead because you are the anchor of the scrum but I am enjoying it because it has got to be good to be able to play in the two positions."






