England lock Courtney Lawes is in danger of missing the entire Six Nations campaign after sustaining a shin injury.
The 23-year-old has returned to club Northampton Saints after making a brief return from a knee injury during England's 12-19 defeat to Wales last weekend.
"It's unfortunate for Courtney as he had just really got back into training with us but we have to listen to expert medical opinion," said interim coach Stuart Lancaster.
"If that means he has to keep the weight off his right leg to help him recover then we have to respect that and work with Saints to manage his recovery."
It is unclear how long Lawes will be sidelined for, but it is likely to be a number of weeks.
