England second row Maro Itoje has had surgery on the fractured jaw he suffered playing for Saracens against Harlequins on Sunday.
It is understood Itoje has fractured his jaw in two places, and has had two metal plates inserted in his face.
The 23-year-old will visit a specialist on Thursday to determine an exact recovery time.
An early prognosis is he will be out for about eight weeks - England start their Six Nations on 4 February.
That match - away to Italy - is eight and a half weeks from today.
Itoje, who has 14 caps, started every match as Eddie Jones' side won the 2017 title, but only featured in two autumn Tests as his playing time was managed.
After a heavy schedule that included starring for the Lions as they drew their series 1-1 away to New Zealand in the summer, the versatile forward was rested for England's opening fixture against Argentina, came off the bench against Australia and started the victory over Samoa.
He was forced off in the 48th minute of Saracens' 20-19 Premiership defeat by Quins at The Stoop after a collision with Mike Brown.
The world player of the year nominee is set miss Saracens' next four European Cup games and three Premiership matches, including the trip to Leicester Tigers in the Premiership on 24 December.
Source: BBC Rugby Union News