Matt Giteau is hardly David to Sam Burgess' Goliath, but he's ready, with nearly a century of Tests to his name, to take down the giant should they go head to head in all-important Pool A clash between England and Australia at Twickenham on Saturday.

"I think everyone has size on me," Giteau laughed when told he would give up nearly 20cm and 31kg to Burgess.

"That's nothing new. I'm used to always playing guys that are bigger than me. It's just a matter of trying to deal with that and looking for my own areas that I can improve on or how I can impose myself on the game."

Giteau has won 97 Test caps in his 13-year career at the top, coming out on top more often than not against rivals of all sizes, and Wallabies backs coach Stephen Larkham notes he is "really dogged" in defence.

Matt Giteau, Quade Cooper© (Photo by Chris Hyde/Getty Images)

"He puts his body on the line 100% of the time so it will be a great match-up. He's certainly not going to take a backwards step."

Burgess was a controversial selection in England's World Cup squad, having played just one Test following his switch from rugby league at the end of last year. And he had played less than two hours of international rugby ahead of his second Test start against Wales on Saturday. But he has been praised for sparking England's attack with direct running and offloads - firstly from the bench against Fiji, and then from the starting whistle against Wales - and Giteau is impressed by the former South Sydney star's development in union.

Giteau likened Burgess' impact to that of another code-hopping star - All Blacks centre Sonny Bill Williams.

"He's very similar to Sonny, not in the way they play because they may play a little different, but they are both great athletes," Giteau said. "Just because of his size, he attracts defenders. He's an athlete and he played a bit of back-row for Bath. I think he understands the rucks and the style of game that they're trying to play.

"Defensively, he's always going to be solid. And in attack, he adds a different element with his offloading game."