JAMIE Roberts admitted he was "shaking for 80 minutes" when England and Australia locked horns last weekend and the powerhouse centre says the nerves are still jangling despite Wales safely making it through their World Cup group of death.

The Wallabies’ 33-13 win at Twickenham dumped the hosts out of their own tournament and set up a showdown for Pool A top spot in London on Saturday.

The winners face a probable last-eight appointment with Scotland or Japan while the losers are set for South Africa in the quarters with the prize of a semi-final against the All Blacks.

Roberts watched the England versus Australia game in the clubhouse at Rosslyn Park after watching friends Adam Frampton, the former Newport lock, and Scott Sneddon, the ex-Cross Keys and Newport fly-half, in action.

He was delighted that the Aussies did Wales a favour but is quick to stress that the pressure is still on for Saturday.

"I was shaking for 80 minutes," Roberts said. "It was like playing a game, expending as much energy.

"When it got to 20-13, I am sure Wales were panicking a bit, but Australia came through, so we are delighted to get through to the quarters.

"But it doesn't take the importance off this week. All is still up for grabs - it's a huge game."

"It is a brutal pool, and it was always going to be," Roberts added. "That's what makes the World Cup so exciting - they are such fine margins.

"The question is being asked of England not qualifying. We beat them by three points. We could have lost that game and England could have been going through and the questions asked of us.”

Wales must halt a run of 10 successive defeats against Australia, having not toppled the Wallabies since November 2008 when Roberts suffered a fractured skull in a collision with Stirling Mortlock.

“When they get things right in attack, then they are one of the best teams. It's one of the biggest challenges in defence that we have faced,” said Roberts.

"A few of the boys have experience defeating Australia in Australia (with the 2013 British and Irish Lions), and I remember in 2008 playing against them with Wales.

"You look back at the last seven years, and it's the same old story. There is no hiding from that. The last 10 minutes in games against them have killed us on many occasion, and hopefully what's on the line this week will bring out the best in us."