Maro Itoje will miss the Guinness Six Nations matches against France and Wales due to a knee injury but could return for the final rounds of England's title quest.
Itoje suffered medial ligament damage in Saturday's 32-20 victory over Ireland in Dublin with a scan revealing a grade two tear that prevents him from playing in the next two rounds.
"Maro Itoje is expected to be available towards the end of the tournament," a Rugby Football Union statement read.
Itoje's Saracens team-mate Nick Isiekwe has been called into England's 35-man training squad assembled to begin preparations for Sunday's visit of France to Twickenham.
Courtney Lawes and Joe Launchbury are competing to fill the vacancy in the second row alongside George Kruis.
Itoje will remain at the squad's Surrey training base to continue his rehabilitation but could be involved in the last two games of the Championship against Italy and Scotland.
The 24-year-old sustained the injury to his right knee in the second half of England's remarkable win at the Aviva Stadium when being cleared out of a ruck by Ireland flanker Peter O'Mahony.
He was ruled out for five weeks after suffering a chipped patella to the same knee in the build up to the autumn series, playing throughout November until the nature of the injury was discovered.
