The most eagerly-awaited fixture of Pool C will be played out at Eden Park on Saturday when the Irish collide with Tri Nations champions Australia.
The Wallabies, second favourites to win the World Cup, have been in ominous form, but Murphy is adamant his team-mates can defy recent results to produce an upset.
"It feels like there's a big performance in the team," the Leicester captain said.
"We have some fantastically talented players, some guys who can play really good rugby. We can take it on another gear or two against Australia.
"We'll be up against it as we're playing one of the best sides in the world, but there's the belief that we can win this. The guys are all confident."
Murphy rates Australia's three-quarters as the most dangerous in the game and is full of admiration for the likes of Will Genia, Quade Cooper and Adam Ashley-Cooper.
"The Australian backline are awesome across the board. Australian rugby for many years has produced fantastic backs," he said. "They're tremendously talented and are great at breaking teams down.
"They're not a bad bunch to boot either, so they're thoroughly unlikeable!
"They're probably the most potent attacking backline in the world. They have pace, power and are intelligent players to boot."
Ireland backs coach Alan Gaffney has ruled out devising a special strategy to deal with Cooper and Genia, who are currently the game's outstanding half-back combination.
"Quade is a player who's developed very well over the past 18 months," he said.
"He has a lot more maturity in the way he plays the game. He's got exceptional skill levels and has fantastic vision. He's world class and is very difficult to handle.
"Will Genia is in absolutely outstanding form. He is some player, as he's shown right through the Tri Nations and over the last two years.
"But Australia have so much potency that we can not afford to concentrate on one or two players. We've got trouble across the board.
"Australia are very exciting, there's no doubt about that. We know the enormity of the task, but we believe we're up to it if we play our very, very best
"In recent times we haven't been there and have been disappointing in what we've done, but we can challenge them.
"We know the performance is within us."
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