Number eight Nick Easter faces a race against time to be fit for NEC Harlequins' clash with London Irish on April 7.
A neck injury suffered in England's win over France at Twickenham earlier this month ruled the 28-year-old out of Saturday's defeat in Wales.
Easter has been told that the compressed disc he picked up during the first half of the 26-18 triumph could keep him out of action for three weeks.
The Dulwich College old boy said: "I played most of the France game with the problem after getting a bash on the head early on - and I thought it would wear off.
"Hopefully I will be ready for Irish, but it could be touch and go. I have got to be careful because I don't want to come back too soon and risk missing the rest of the season."
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