England lock Maro Itoje and wing Jack Nowell are fitness doubts for the Six Nations clash against Italy at Twickenham on Saturday.
Itoje, 24, who had been recovering from a knee ligament problem, was recalled to coach Eddie Jones's squad Monday after Courtney Lawes was ruled out of the tournament due to a calf strain.
However, the Saracens forward limped out of training on Tuesday after picking up an injury on the same knee saw that him sidelined for England's last two matches in the competition.
Nowell suffered a shoulder injury during England's 21-13 loss against Wales at the Principality Stadium last month.
The RFU confirmed in a statement that Bath's Charlie Ewels has been called up as an injury cover for Itoje whilst Gloucester's Ollie Thorley is cover for Nowell.
"Maro has had a minor tweak and the medical staff are taking a look at it," England attack coach Scott Wisemantel said. "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."
Information from Reuters was used in this report.