England coach Graham Rowntree has warned his men they will be facing one of the greats in Ireland's Brian O'Driscoll.
Stuart Lancaster's side will take to the Twickenham field on Saturday for the first time in the 2014 Six Nations - facing visitors who have outmuscled Italy and Wales in an encouraging start to the campaign.
O'Driscoll has been instrumental for Joe Schmidt's men, most notably when proving his point to Wales coach Warren Gatland, who controversially dropped him for the final Test of the 2013 British & Irish Lions tour to Australia.
And Rowntree, who was part of Lions staff Down Under, said of the 35-year-old: "Beating us will mean everything to him. What a player... he's an icon.
"He's a thoroughly professional player and I really enjoyed working with him. As a man he's exceptional.
"You hear the way Owen Farrell, Luther Burrell and Billy Vunipola speak about him, you can tell the respect they have for him.
"He took that disappointment in the Lions series on the chin.
"I remember the day when he was left out of the team, that afternoon he was sat down with the guys going through things on the computer, helping them and coaching them. That speaks volumes about the man."