Wasps captain Joe Launchbury has been ruled out of England's opening Six Nations match with France next weekend because of a knee injury.
The 28-year-old forward sustained the injury in the Challenge Cup defeat by Bordeaux-Begles a week ago and will not be available for the trip to Paris.
He hopes to be fit for the Calcutta Cup match with Scotland on 8 February.
Launchbury was part of England's World Cup squad last autumn but made only one appearance, against the USA.
Eddie Jones and his Six Nations squad have held a World Cup debrief at their training camp in Portugal guided by Andrea Furst, the team psychologist.
England reached their first World Cup final for 12 years with a superb 19-7 win over three-time champions New Zealand, before losing 32-12 to South Africa.
Bath flanker Sam Underhill said the players needed to "unpack anything that might be there" from the final but look back positively on their time in Japan.
"The aim ultimately is to learn from the World Cup and be at peace with it. There has got to be an end point to that surely," the 23-year-old said. "The overriding message from the review was that it was a brilliant experience."