One minute's silence will be observed before the Pool C showdown at Stadium Taranaki and both teams will wear black armbands.
On the morning of the game the Eagles will also attend a memorial service in New Plymouth.
The terrorist attacks on New York a decade ago have been discussed within the Irish camp and O'Connell knows the occasion will galvanise the USA.
"A lot of guys asked each other at dinner during the week where they were when it happened," said the Lions captain.
"We're certainly aware of it. It focuses our minds as well because we know how motivated they'll be for the occasion.
"It's a very poignant occasion. Hopefully it will be a good game tomorrow that's well remembered.
"You use everything you can to motivate yourself and I'm sure they'll have it channeled in the right way."
USA scrum-half Mike Petri, who was born and raised in New York, feels the poignancy of tomorrow as strongly as anyone.
"It's obviously a very significant day for us and for all our fans and supporters back home," he said.
"It will be very emotional and I do believe that it can only be a positive thing for us to follow that emotion.
"The opportunity to represent your country on such a day as September 11, albeit the 10th anniversary of the attacks, is a huge honour.
"I'm really looking forward to paying some respects to all the Americans around the world who are affected or not affected by what has happened.
"It's certainly come to the forefront lately. I'm reminded of it all the time when I'm back home.
"One of my best friends lost his father. He was a firemen and was killed. Guys I grew up with lost brothers and family members.
"There are constant reminders all the time. I pass by Ground Zero almost daily.
"You live with those things every day. With this game coming up, there has certainly been a bit more attention to it publicly."
Les Kiss, Ireland's defence coach, stresses that the trauma of 9/11 was felt across the world.
"It's quite emotional for a lot of people in the world. The Irish rugby community lost some people in it, as did the US rugby community," he said.
"It's a grave thing to remember. Will the emotion take over? I don't think so. (USA coach) Eddie O'Sullivan's smart enough to keep that in check.
"But we have to recognise that it's a terrible thing that happened 10 years ago.
"Hopefully we can look at it in a good light at the end of the game."
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