Skipper Brian O'Driscoll admitted Ireland would have to improve a lot after Sunday's uninspiring 22-10 opening World Cup win over the USA.
The Irish face Australia next in Pool C and O'Driscoll did not hide from the fact they had underperformed.
"We did not play well, we had to fight for the win. We couldn't get any continuity and were a bit loose.
"It is good to get 80 minutes under your belt. We can work on bad aspects of our game during the week."
Irish coach Declan Kidney admitted Ireland had not been particularly impressive but said he was delighted with the win.
Kidney looked forward to the next game against Australia, saying: "Another big one - that is why you get into it. This is a fantastic tournament. It is a six-day turnaround to Eden Park."
Former Ireland boss Eddie O'Sullivan, now coach of the USA, was delighted by the commitment shown by the Eagles.
"We fought our way from the first minute until the last. We were punch drunk at times, but we were very spirited," he said.
"The lads put in a huge performance. All it takes is for a couple of lads to fail and then the floodgates open and you've conceded 20 or 30 points.
"There were times when I thought that would happen but the guys just dug deeper and deeper."