The Azzurri skipper leads the Barbarians against England at Twickenham tomorrow knowing he must soon turn his mind to more serious matters.
Italy have never previously qualified for the knockout stages of the tournament but feel they have a genuine chance of breaking new ground in New Zealand this autumn.
Drawn in Pool C alongside USA, Russia, Australia and Ireland, Parisse has revealed the fixture against Brian O'Driscoll's men on October 2 has been identified the pivotal encounter.
"We have a tough group but our objective is to qualify for the quarter-finals for the first time," said the Stade Francais number eight.
"Our game against Ireland is the last match of the group. Even if we lose to Australia we have the potential to qualify if we beat Ireland.
"But we also need to beet America and Russia of course."
Italy are convinced they can prevail after going desperately close to beating Ireland during this year's RBS 6 Nations.
It took a last-gasp drop-goal from substitute Ronan O'Gara to snatch a dramatic 13-11 victory at the Stadio Flaminio.
"We were very close to beating Ireland in Rome. We are not far off them in standard," said Parisse.
"But then when you see a side like Leinster playing well in the Heineken Cup, you know Ireland will be in top form for the World Cup.
"There will be a lot of pressure because both teams will need to win to qualify. I hope this time we can beat them."
Sergio Parisse insists a lack of familiarity will ensure the Barbarians keep it simple when they meet England tomorrow.
"It's not easy to play together because we come together so quickly, but the coaches want us to do simple things. That way it's easier to adapt," he said.
"We only have a few plays from scrums and line-outs and after that we just play rugby.
"We have to rely on our ability. It should be a good match against England.
"It was unexpected for me to be named captain and it's a great honour. I'm really looking forward to playing against England.
"Our side is full of big players. We've had a lot of fun during the week in training, I've enjoyed it."
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