England wing Jonny May appears set to miss the entire RBS 6 Nations with the knee injury sustained in Gloucester's Aviva Premiership draw with Harlequins.
May limped off in the 42nd minute at Twickenham last Sunday after incurring the injury while kicking the ball and it has now emerged that he must go under the knife.
"Jonny has suffered a pretty significant knee injury that requires surgery," Gloucester director of rugby David Humphreys told the Gloucester Citizen.
"He's seeing a specialist on Tuesday and based on the outcome of that we will have a much clearer picture on what needs to be done.
"Most importantly, it is a huge blow for Jonny to suffer an injury like that at this stage of the season. But knowing him and his dedication, he will leave no stone unturned in his recovery."
England open their RBS 6 Nations against Scotland on February 6 and given Humphreys' bleak prognosis it seems highly unlikely that May will play any part of the Championship.
It is another twist in the roller-coaster career of the 25-year-old, who alongside Anthony Watson re-established himself as England's first choice wing in the second half of this year with three tries in six appearances made in the build up to and during the World Cup.
Head coach Eddie Jones has already lost centre Henry Slade, back row Dave Ewers and prop Kieran Brookes to injury for all, or part, of the Six Nations.