England’s Billy Vunipola is likely to miss the Six Nations with a knee injury which will keep him out of action for at least three months.
The Saracens number eight, 24, tore cartilage during England’s 27-14 defeat of Argentina at Twickenham on Saturday.
He had surgery on Sunday and is not expected to recover in time for the Six Nations, which begins on 4 February.
England will play Australia at Twickenham on Saturday in the last of their autumn internationals.
“Billy’s been absolutely fantastic for England over the last 11 months and we wish him a quick recovery,” said England head coach Eddie Jones.
“He’s a very influential player in the set-up and there’s no doubt he’ll be missed for the game against Australia.
“We’ve had five or six frontline players missing throughout the series, so I’ve no doubt we’ll adapt and work that little bit harder this week. I’m sure the players will respond to this by going up a level and peak for this game.”
Vunipola was also set to be a key figure when Premiership leaders Saracens resume their defence of the European Champions Cup next month.