Maro Itoje is to miss at least a chunk of the Guinness Six Nations due to the knee injury sustained against Ireland on Saturday.
Press Association Sport understands that a scan has revealed Itoje suffered a grade two medial ligament tear that usually requires two to four weeks of rehabilitation.
The prognosis means that the British and Irish Lions lock could be available for the finale to the tournament against Scotland on Mach 16 – and potentially earlier.
Itoje was on Monday afternoon due to see a specialist to be given a clearer picture of when England can expect him back.
Losing their second row talisman for Sunday's clash with France and almost certainly Wales a fortnight later is a substantial blow to Eddie Jones' men.
Itoje is crucial figure in England's pack and his power and work rate were key in subduing champions Ireland at the Aviva Stadium.
Either Courtney Lawes or Joe Launchbury will slot into the starting XV in his absence, partnering George Kruis in the second row.
Lawes made a forceful second-half appearance in Dublin, but, while Launchbury was excluded from the matchday 23, England may want his bulk on from the start.
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