Harlequins fly-half Marcus Smith has been ruled out until the new year with an ankle injury, sustained playing in England's defeat by South Africa.
The 23-year-old started all four of England's autumn internationals.
But he was forced off after 61 minutes of Saturday's 27-13 loss.
"He had a specialist look at him last week and he'll have another one look at him next week but he'll be out for this month," Harlequins head coach Tabai Matson told BT Sport.
"I think early next year we'll get a better prediction on how many weeks he'll be out for."
Smith has made four appearances for Quins so far this season and scored one try.
He is set to miss at least the team's first two European Champions Cup fixtures, away to Sharks and at home to Racing 92, as well as the Premiership match with Bristol at Twickenham on 27 December.
England are due to have a pre-Six Nations training camp over the new year period, while they open their campaign against Scotland on 4 February.