England's Moody in doubt for Six Nations
Moody limped off during the second half of his club Bath's European Cup victory over Italian side Aironi last Saturday and the former Leicester flanker is set to miss England's opening Six Nations games against Wales, Italy and France.
England manager Martin Johnson has already lost lock Courtney Lawes and flanker Tom Croft from his initial Six Nations plans through injuries.
Moody, 32, has won 66 England caps, and his absence will be keenly felt by Johnson.
"It is always disappointing to lose a player and leader of Lewis' calibre," said Johnson. "But as I have consistently said good teams adapt to injuries, and that is what we intend to do.
"While this could still mean Lewis plays a role in the Six Nations, it does mean that another player gets the chance to step up and make it hard for him to get the shirt back."
England launch their Six Nations campaign against Wales in Cardiff on February 4, with Lawes (knee) and Croft (shoulder) also confirmed absentees.
Johnson will announce his captain in the week leading up to the Wales game, with Moody now remaining at Bath for his rehabilitation.
He could though, be available for England's final two Six Nations games against Scotland and Ireland in March.
Wales have also been hit by problems ahead of the tournament opener. Prop Gethin Jenkins is out of the whole competition because of a toe injury and scrum-half Richie Rees is banned until March 31.
Wales boss Warren Gatland has additionally seen Gavin Henson's Test comeback hopes put on hold by a calf muscle problem, and Gatland is anxiously awaiting news on tighthead prop Adam Jones, who suffered an elbow injury during Ospreys' European Cup defeat against London Irish two days ago.
Jones is expected to undergo a scan on Tuesday, amid initial unconfirmed reports that he could be out for up to eight weeks.