England face being without their first choice second row pair for their entire Six Nations campaign after Courtney Lawes was ruled out for the opening fortnight of the championship following confirmation he requires surgery on a chipped ankle bone.
The Northampton Saints lock's return from the ankle problem has been constantly delayed since his last appearance against Leicester Tigers in December, and the decision has been taken for the 25-year-old to go under the knife.
Lawes will therefore definitely miss the Six Nations opener against Wales in Cardiff on 6 February and the visit of Italy on 14 February but could yet be fit for the clash with Ireland on 1 March at the Aviva Stadium.
"Courtney failed to recover from the ankle injury and he will have an operation on Monday," Saints director of rugby director Jim Mallinder.
"The bone needs to be cleaned out and he will miss the first few rounds of the Six Nations. A piece of bone chipped off during the Leicester game and his loss is a blow for us, for Courtney and for England. He is a key player. We expect him to return to action while the Six Nations is still going on."
In order to prove his fitness for the second half of England's Six Nations campaign, Lawes will surely have to feature in either of Northampton's matches against Bath and Harlequins which are sandwiched between the fortnight break in the tournament.
Joining Manu Tuilagi [groin] Joe Launchbury [neck] and Ben Morgan [broken leg] on the sidelines, Lawes becomes the third player to undergo surgery eight months out from the World Cup and will miss a significant chunk, if not all of the Six Nations.
Coach Stuart Lancaster names his Six Nations squad on Wednesday and though Lawes is likely to be included, George Kruis, Dave Attwood and Geoff Parling will take on the extra workload.