The contingent of travelling fans was swelled by The Tullow Boys, a 25-strong legion of fans from the hometown of star flanker Sean O'Brien.
"You can't miss 'em, you won't miss 'em," he told the Irish Times.
Yesterday Irish fans packed out bars in town, with one group of tourists having their beer laid on free.
Jim Kelly, 77, had travelled to New Zealand from County Armagh for the cup. "All we're going to do is winning," he chortled. "We're on a winning streak."
He didn't want to pick a score for the Ireland-Russia game today. "A win would be enough".
A publican liked the music of travelling buskers The Craic Band so much that he shouted their drinks and invited them to come back to play today.
One of the musicians, known only as Paddy, said the band were surviving on the generosity of pub owners and generous bar patrons.
"It's been great craic, New Zealand's been very good to us and, of course, our Irish brothers and sisters think it's brilliant," he said.
Ticket sales were evenly split between local buyers, those around New Zealand, and international guests.
Organisers said there was potential for traffic delays and congestion, given the amount of people heading to Rotorua's International Stadium.
Rugby fans are being urged to leave plenty of time to drive to their destination and to get to the stadium well ahead of the 6pm kick-off.
The Russian team won't be without support, with a small group of New Zealand fans touring with the side.
Argentina will play a bagpipe-less Scotland in Wellington in a match which is likely to decide New Zealand's quarter final opponent at 8.30pm.
- additional reporting Rotorua Daily News
