Sale Sharks star Robinson, who has scored three tries in this seasons tournament, could be a doubt for the Croke Park clash.

He is being treated by England medical staff at the world champions Bath University base, with his condition to be reassessed tomorrow ahead of departure for Dublin.

Head coach Brian Ashton has called up 23-year-old Strettle, a key performer in England Saxons victory over Italy A earlier this month, as precautionary cover.

England assistant coach Mike Ford said: Jason got a bit of a knock and has gone off to see the doctor. Hopefully, he will be okay.

Robinson, capped 41 times, skippered England on their last Dublin mission two years ago, which proved his final Test match before coming out of international retirement for this seasons Six Nations tournament.

If the 32-year-old is sidelined, then Ashton would probably promote Newcastle back Mathew Tait from replacement duty, although a full Test debut for Strettle could not be ruled out.

While England wait for an update on Robinson, Ford underlined the threat posed by Irelands celebrated midfield pairing of Brian ODriscoll and Gordon DArcy.

ODriscoll has recovered from a hamstring problem that meant he missed the 20-17 defeat against France earlier this month.

His partnership with DArcy poses arguably the biggest danger to an England team targeting a first Dublin victory since 2003.

Ford added: We knew Brian would be fit, so we have been planning to counter the threat.

ODriscoll is the top try-scorer in Irish international rugby history, and his record speaks for itself.

As a defensive coach, it is DArcy, really, who worries you the most. He has got great acceleration off the mark; he can step off both feet and he really is the catalyst for Ireland to go forward.

At the moment, Brian is playing a kind of support role to what DArcy is doing. They are both great players.

Ford spent four years as Irelands defence co-ordinator - his chief role with England since last May - and has questioned their ability to cope with being favourites, a mantle they hold going into Saturdays encounter.

Ford said: During the four years I was there, they got labelled as a team that couldnt handle the favourites tag, and they didnt do that against France a fortnight ago.

They are the favourites again this week, so there is a lot of pressure on them to win this game at Croke Park.

We are the underdogs. Weve not beaten Ireland since 2003 so we are going out there and know we have got to play better than we did against Italy two weeks ago.