Ireland captain Brian O'Driscoll has called on his side to improve after their unconvincing win over the USA.
The Irish beat the unfancied Americans 22-10 in their opening Pool C match of the World Cup in New Plymouth on Saturday.
The win came courtesy of two Tommy Bowe tries and one from Rory Best, with the USA's Paul Emerick crossing for a late consolation, as Ireland failed to pick up an anticipated bonus point.
"We didn't play well, we had to fight for our win," said O'Driscoll.
"I suppose we got the win but we have a hell of a lot to improve on. We couldn't get any continuity. We were a little bit loose."
Ireland could only finish third in the 2011 Six Nations and have since lost all four of their World Cup warm-up matches.
They are next in action against the world number two ranked side Australia on Saturday, September 17.
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