None of the concerns that hang over the Irish squad following a troubled build-up to New Zealand were addressed during Sunday's unconvincing 22-10 victory over the United States.
Their Pool C campaign continues with Saturday's critical Test against Tri-Nations champions Australia at Eden Park.
On current form it is an encounter they have little chance of winning, but McNaughton believes that if they click, Ireland can topple the Wallabies to put one foot in the quarter-finals.
"The guys have played against Australia before. They know them," he said.
"There's a level of confidence that on our day, when we play well and fire on all cylinders, we can beat Australia.
"We have the ability and the team to beat Australia.
"We have to play very well and better than we have done over the last four or five matches.
"We'll have to improve on what we did yesterday, but do seem to produce our best when our backs are against the wall.
"Underdogs is not a position we'd go looking for. We're clearly underdogs based on the record over the last few games, but that doesn't worry us.
"But there's a strong belief that if we get all parts of our game right, we can provide very fine opposition for Australia."
There was a sense of deflation at Stadium Taranaki as the World Cup's oldest team failed to produce the emphatic start to the tournament they desperately needed.
Conditions were poor and the USA were charged by the 10th anniversary of September 11, but they should still have been dispatched with greater conviction.
"We've all had a chance to reflect and watch the performance on video," said McNaughton.
"We were disappointed, disappointed not to get the bonus points and execute a few more try opportunities that we had.
"We're happy with the win. All weekend we saw the so-called lower ranked teams put it up to the higher ranked teams.
"Everybody going into the game knew we were going into a game and not a practice session. That's the way it turned out.
"We're disappointed we didn't get the fourth try, despite having a number of opportunities.
"We didn't get it and there was some poor handling associated with that. Nevertheless, we're happy to win and must move forward now."
Prop Tony Buckley will undergo a scan on Monday afternoon on the shoulder injury he sustained in New Plymouth.
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