England have called Harlequins' Dave Strettle into the squad for Saturday's game with Ireland after Jason Robinson suffered a neck injury in training.
Robinson receives treatment after the incident in training
Sale captain Robinson, who has scored three tries so far in this season's Six Nations championship, sustained the injury training with the squad in Bath.
The England management will re-assess his condition on Thursday.
Strettle, 23, joined from Rotherham in summer 2006 and played in England Saxons's win over Italy A this month.
Robinson's absence would be a major blow given his try-scoring form since ending his retirement from Test rugby and returning to the fold.
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, was captain when England last played Ireland in Dublin two years ago - which turned out to be his last Test before he initially decided to retire.