After signing off from the RBS 6 Nations by ruining England’s Grand Slam dreams Ireland’s preparations have been rocked by two defeats to France in between losing to Scotland and Martin Johnson’s men.

Despite their struggles O’Brien and co. will be heavy favourites to defeat USA in their opening pool game on September 11before facing Australia, Russia and Italy.

And the 24-year-old, who experienced European success by helping Leinster claim the Heineken Cup in May, insists there’s no reason why Ireland can’t claim their first Webb Ellis Trophy.

“I think we can go the whole way if we click and we play to our potential,” said O’Brien.

“It’s about getting our own stuff right. A lot of people are worried about the last four games but we certainly aren’t and I can say that honestly.

“If we play the rugby that I know we can play, we’ll be a hard team to stop.”

“I know we weren’t that consistent but at the same time we had a different team every week, lads are getting used to each other.

“That’s not to make any excuses. We didn’t win the games, as simple as that.

“But the World Cup is a different story, it’s a new start and our preparations will begin the minute we get over there for the first game.”Ireland are heading into the World Cup on the back of four straight defeats but back row Sean O’Brien insists the form book will go out the window in New Zealand.

After signing off from the RBS 6 Nations by ruining England’s Grand Slam dreams Ireland’s preparations have been rocked by two defeats to France in between losing to Scotland and Martin Johnson’s men.

Despite their struggles O’Brien and co. will be heavy favourites to defeat USA in their opening pool game on September 11before facing Australia, Russia and Italy.

And the 24-year-old, who experienced European success by helping Leinster claim the Heineken Cup in May, insists there’s no reason why Ireland can’t claim their first Webb Ellis Trophy.

“I think we can go the whole way if we click and we play to our potential,” said O’Brien.

“It’s about getting our own stuff right. A lot of people are worried about the last four games but we certainly aren’t and I can say that honestly.

“If we play the rugby that I know we can play, we’ll be a hard team to stop.”

“I know we weren’t that consistent but at the same time we had a different team every week, lads are getting used to each other.

“That’s not to make any excuses. We didn’t win the games, as simple as that.

“But the World Cup is a different story, it’s a new start and our preparations will begin the minute we get over there for the first game.”