Sam Underhill will miss the entire Six Nations
having had surgery on his ankle.
The 22-year-old Bath flanker will be out for up to three months, after injuring himself on December 30 against Leicester.
Underhill was already set to miss the opening games against Ireland and France
, but Bath confirmed on Friday the blow was more severe than first though and the flanker had gone under the knife.
That means he will miss the whole Championship, leaving England in something of a quandary at openside flanker once more.
Sale's Tom Curry, 20, is the only true No 7 left. He started four times against South Africa, three away and one at home, before injuring himself last year.
Underhill then starred against New Zealand and Australia, with Newcastle's Mark Wilson playing openside against Japan.
Eddie Jones picks his Six Nations squad on Thursday, January 17.
A Bath statement read: 'Sam Underhill has had surgery on his ankle and is expected to be out of action for up to three months.'