England lock George Kruis has been ruled out of the Six Nations with a knee ligament injury.
The 26-year-old Saracens forward will have surgery on Tuesday and will be out for up to three months.
However, prop Mako Vunipola will join up with Eddie Jones' squad this week as they prepare to face Wales on Saturday.
It is hoped the Saracens man, 26, who is recovering from a knee problem, will be fit to play some part in the latter stages of the championship.
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Kruis, who had only just recovered from a fractured cheekbone, missed England's Six Nations opener against France on Saturday after picking up the injury in training on Tuesday.
The set-back is a blow to Kruis' chances of making Warren Gatland's British and Irish Lions squad, which is due to be named on 19 April.
The Lions' tour of New Zealand begins in June.
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