Ireland fullback Geordan Murphy believes that former coach Eddie O'Sullivan will use his "inside knowledge" to better prepare his USA players for Sunday's opening World Cup clash in New Plymouth.

O'Sullivan was in charge of the Irish team that failed to make it out of the group stages in France four years ago before taking over as coach with the American Eagles for the tournament in New Zealand.

As luck would have it, the two teams were drawn in the same Pool C with their encounter first up on the tournament's opening weekend.

Murphy said that he fully respected O'Sullivan for his years as coach of the Ireland side, but that it would "not really be a massive factor for us."

"He's probably got a lot of inside knowledge on the way our guys like to play and I'm sure he'll be tipping his team off to our strengths and weaknesses, so we've got to do our homework on those guys and give them the full respect that they deserve," Murphy said.

Adding to the emotion for the hugely underdog Americans is the fact that Sunday's game will come on the 10th anniversary of the deadly 9/11 terrorist attacks on New York and Washington.

The International Rugby Board (IRB) has already announced that a minute's silence honouring the victims will be held prior to Sunday's game and Ireland's players are expecting that to inspire the Americans.

"Obviously they're going to be charged and the first 10 minutes I'm sure will reflect that," said hooker Rory Best.

"From an Irish point of view we have to make sure that we're able to match their physicality and intensity, especially in that first 10 minutes."

Ireland's preparations for New Zealand went poorly with four straight defeats to Scotland, France (home and away) and England.

But Best said the squad's training camp in the South Island holiday resort of Queenstown had gone well, and that they would be ready for the challenges to come against the Americans followed by Australia, Russia and Italy.

"We had two reasonable run-outs before today (Tuesday), but there's no doubt today, you could feel it, you could see it, there was a big step-up in intensity," he said. "Everyone knew: 'game week' and this is why we're here."

AFP