With the world's best centre Brian O'Driscoll leading the charge, Wallabies coach Eddie Jones expects Ireland to throw off the shackles in their final Rugby World Cup pool game on Saturday.

While the Wallabies blitzed Namibia 142-0 in Adelaide, barely raising a sweat as they ran in 22 tries, the Irish scrambled to a 16-15 win over Argentina in a grinding, see-sawing contest to secure a quarter-final berth alongside Australia.

In a more traditional Test rugby contest, only one try was scored, by Ireland flanker Alan Quinlan whose tournament ended when his shoulder was dislocated as he was tackled across the line.

But Jones believes with the pressure to make the play-offs lifted, Ireland will be a completely different side against Australia at the Telstra Dome on Saturday night.

He didn't think they would have any trouble backing up for another tough match, which will decide who finishes top of the pool and avoids a quarter-final showdown with big-gun France.

"Both teams played it like a grand final because the teams were concentrating on the result rather than the game ... now they're in the quarter-finals we'll see an Ireland side without the shackles and they'll probably be a lot more expressive and a lot more free than they were last night," Jones said.

O'Driscoll, who gave Australian rugby fans a taste of his extraordinary talents on the British and Irish Lions tour in 2001, has had a quiet tournament so far, outshone in the Argentina match by his hard-running centre partner Kevin Maggs.

Jones said the 24-year-old wasn't far from hitting his straps, and predicted it could happen against the Australians.

"He's certainly probably been below his best but you know with a guy like him he's only probably one ball touch away from being at his best.

"He's a great athlete and I think he's going to really respond to a fast surface at Telstra Dome."

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