Dylan Hartley classes Saturday's mouth-watering Six Nations clash against Ireland as England's first "proper" game under Eddie Jones.
England secured back-to-back wins over Scotland and Italy in the opening two games of their Six Nations campaign.
Defending champions Ireland head to Twickenham in search of their first victory of the tournament and without key players due to injury.
But England captain Hartley is well aware of the threat Joe Schmidt's side pose.
"Now we have got those two games out of the way we can play a proper Test match, at Twickenham, against the holders. It's a proper game," said the hooker.
"I wouldn't have said that before the tournament. I am only saying that because we have got those first two games out of the way.
"The biggest challenge when we first got together was having just 10 days of training and then playing a Test match away against a good, in-form Scotland team.
"Then you have the potential banana skin of Italy who England have never lost against, so that is another challenge. Now those are done, I can say this is a proper game."