The former Hurricanes flanker Brad Shields is a doubt for the start of England's Six Nations campaign.
Shields pulled out of Wasps' Champions Cup match against Leinster raising a question mark about his availability for England's Six Nations opener against Ireland next month.
The 27-year-old, who started England's November internationals against South Africa, New Zealand and Australia, has a side strain according to his club.
They did not offer a time-frame for his return from the injury.
England are already waiting on the fitness of first-five Owen Farrell, who is to have minor surgery on his thumb.
Farrell is due to be back in action in seven to 10 days, a recovery that would enable him to play against the defending champions and Grand Slam winners in Dublin on 2 February.
However the ligament repair may prevent him from working with his team-mates on a training camp in Portugal that begins on Wednesday.
While Chris Robshaw and Sam Underhill are out of contention for the meeting with Ireland, coach Eddie Jones' back-row options have been bolstered by the return of Billy Vunipola and Tom Curry from arm and ankle injuries respectively and Nathan Hughes from a suspension.