Click here to listen to Luke Charteris
Wales play their second Test match on tour in Chicago on Saturday. The tough-to-please Holley is determined the Dragons will plug any defensive frailties which were exposed by the hard running Canadians last weekend.
"My focus is on defence. We did quite well in the weekend but still conceded two sloppy tries. We've got to focus on not conceding any on Saturday," said Holley.
Holley added he is enjoying his coaching role on tour where he is working with Robin McBryde and Neil Jenkins for the first time.
"At regional level a major part of your role is to develop players and help them improve their skills. I've tried to being that to the table here on tour but clearly you've got a short space of time and it's about attention to detail for two very important test matches."
Newport Gwent Dragons second row Luke Charteris, who arrived in Chicago earlier this week after answering a call to replace the injured Bradley Davies, is hoping to add to his 13 caps against the USA.
"Obviously the two boys who are already here are front runners for a start, but with Brad unfortunately getting injured, I might have a change of getting on the bench," he said.