Robbie Deans has challenged his "Jekyll and Hyde" Wallabies to continue delivering after starting their grand slam quest with a tension-filled 18-9 victory over England at Twickenham.

The Wallabies head to Dublin for a boom-or-bust showdown with Ireland next Sunday armed with renewed belief after averting disaster with a stirring second-half comeback at rugby's spiritual home.

Mighty defence, a magnificent man-of-the-match display from rookie halfback Will Genia, some welcome composure and a powerhouse late try to fullback Adam Ashley-Cooper were just enough for Australia to counter the class and inspiration of England's returning hero Jonny Wilkinson.

Playing his first Test in 18 months, Australia's World Cup nemesis threatened to heap yet more misery on the Wallabies after booting the depleted hosts to a shock 9-5 halftime advantage.

In a gripping encounter, Australia continued to trail until Matt Giteau drilled an angled 25-metre penalty goal on the hour, before Ashley-Cooper carried four English defenders over the line eight minutes from time to clinch a desperately hard-fought win.

"England threw everything at us. They tried everything. They tried width, they tried the short route, they tried to turn us and the boys stood up to that test really well. I'm very proud," Wallabies coach Robbie Deans said.

Deans's daring selection of Quade Cooper alongside Digby Ioane as an untried centres pairing reaped rewards, with Cooper's footwork and signature wide passing game - combined with Genia's outstanding service - giving the Wallabies backline an added dimension.

Although they only scored twice, including a maiden Test try for Genia in just his fourth starting appearance - the Wallabies could have had several more with the backline a constant threat to England's vulnerable defence.

"In his first big occasion essentially, Quade has stepped up and done really well. But, as is often the case, it's week two that is the key," Deans said.

The could well have been talking about his entire side, with the Wallabies having struggled throughout his 25-Test tenure to string back-to-back performances together.

During a sorry run of six defeats in seven Tri Nations and Bledisloe Cup Tests this season, the Wallabies followed up a 21-6 triumph over the world champion Springboks with their worst effort of the year, a 33-6 capitulation against the All Blacks.

"Sooner or later, you've got to get up. We're hopeful that we can create a habit," Deans said, knowing there can be no letdown against Ireland, the reigning Six Nations champions who this season completed their own grand slam sweep of the home nations for the first time in 61 years.

"We go to Croke Park next week against an Irish side that's brimming and that's obviously a venue that historically has proved challenging. It's a great opportunity for us to push on.

"You don't get to be grand slam champions, as they are, lightly.

"So, off the back of that, they'll have a lot of belief. Combine that with playing at Croke Park and they'll take some containing."

Praised by Deans for his newfound maturity, Cooper said it was still premature for the Wallabies to contemplate emulating Australia's famous 1984 grand slammers.

"We've beaten England now, but we've got Ireland, Scotland and Wales to go," he said.

"Until we beat those three teams, we haven't won a grand slam. We're just on our way to playing in a grand slam.

"We know that we've got three weeks of hard work ahead of us."

England coach Martin Johnson said the grand slam was definitely "worth having a crack at".

"It'll be interesting to see if it can be done," he said.

"They're capable of winning any of those Test matches, but adding them all together and doing it, that's what it's about.

"You'd think it would be pretty tough but it'd be a good achievement if they did."