England wing Jonny May will have surgery on a knee injury, meaning he could miss the Six Nations.
May, 25, limped off while playing for Gloucester in their Premiership draw with Harlequins last Sunday.
England start their Six Nations campaign under new coach Eddie Jones against Scotland on 6 February.
"Jonny has suffered a pretty significant knee injury that requires surgery," Gloucester boss 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 of 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."