Andy Robinson's side are desperate to restore a reputation battered by successive defeats by Scotland and France in what has become another disappointing RBS 6 Nations Championship campaign.

The 31-6 thumping in Paris last Sunday marked the lowest point of Robinson's rein and the head coach reacted by axing six World Cup winners.

With so much at stake, O'Sullivan expects the Irish line to be exposed to a fearful early battering and has warned his Triple Crown hopefuls to discard thoughts England are vulnerable.

''England are under pressure and they do need a performance. They have a lot to prove. They'll be very disappointed with their championship overall,'' he said.

''Last week's display in Paris was well below par. If they come out and hit the ground running they'll exorcise their demons.

''They'll want to bounce back and are a very powerful side. There will be a very physical element to their game - they'll come at us early on and see if we're up for the task or not.

''If England click, they can have a really big day out. At Twickenham they are more likely to click than not click. They ran the All Blacks very close last autumn.

''If they reproduce that display they'll be thinking they can see off Ireland. Maybe they won't click because they've made a lot of changes.

''It's hard to know, but England tend not to put bad back-to-back performances together.

''A mantra of Sir Clive Woodward's was the test of a good team lies in how they respond to adversity. That will be what they've talked about.

''The platform has been set up for them to erase a bad performance with a good one. England aren't vulnerable all of a sudden - they'll be more galvanised.''

Ireland were the first team to beat England after they had won the World Cup in November 2003 and the memories of that 19-13 triumph at Twickenham will steel the Irish on Saturday.

Victory would give Ireland their second Triple Crown in three years and continue their run as the RBS 6 Nations' most consistent team of recent seasons.

They still retain a chance of winning the title outright but to have a realistic hope of that Wales must overcome likely champions France in Cardiff.

If France succeed at the Millennium Stadium then Ireland, who are gunning for their third straight victory over England, must win by at least 30 points at Twickenham to be crowned champions.