England back-row Chris Robshaw will miss the Six Nations after he was ruled out for 12 weeks due to shoulder surgery.
Robshaw aggravated an existing shoulder problem in Harlequins' defeat to Worcester on Jan. 1 and will now face an extended spell on the sidelines.
The news will come as a huge blow for Eddie Jones' England as Robshaw started all but one Test in 2016, missing the one-off match against Wales in May.
Jones will now need to find a new blindside in a pack already hit hard by injury.
Mako and Billy Vunipola are set to miss the bulk of the Six Nations with knee injuries while George Kruis is nursing a fractured cheekbone. James Haskell returned from injury on Sunday to play his first rugby since June but only lasted 35 seconds before being forced off with a head knock.
Robshaw, who has won 55 England caps, will leave big boots to fill and Jones may look at shifting Maro Itoje to blindside while Tom Wood, Teimana Harrison, Josh Beaumont, Nathan Hughes and Mike Williams are other contenders for spots in the back-row ahead of their Six Nations opener against France on Feb. 4.