Maro Itoje hobbled out of training on Tuesday to give England an injury scare ahead of their Six Nations game with Italy.
Itoje was expected to make his comeback from the ligament damage sustained to his right knee on February 2 when the Azzurri visit Twickenham on Saturday, but the setback has placed that prospect in doubt.
The British and Irish Lions lock was performing a forwards drill when he grimaced in pain after stepping off his left knee and having fallen to the ground, he then limped off.
The injury was sustained in front of head coach Eddie Jones, who was feeding the forwards the ball as they ran towards the posts.
England attack coach Scott Wisemantel said: "Maro has had a minor tweak and the medical staff are taking a look at it.
"He's being managed day by day anyway, I don't think it's anything serious.
"We've just got to wait and see what the medics say. We'll see how he pulls up tomorrow."
Know more: http://v.duta.us/JlepwgAA