The availability of Billy Vunipola for England's Test against Fiji on Saturday is in doubt, while David Attwood will definitely miss out due to a knee injury.
Saracens number eight Vunipola, so impressive yet again in a long-awaited victory over South Africa at Twickenham on Saturday, was unable to train on Monday due to an unspecified injury.
Attwood, who came off the bench in the 37-21 victory against the Springboks, has been ruled out of England's second autumn international with a knee injury and the lock will return to his club Bath.
Alex Goode, Semesa Rokoduguni, Henry Slade and Teimana Harrison were among the nine players to return to training with the England squad on Monday after they did not make the final cut to face South Africa.
Head coach Eddie Jones will on Thursday name his England team to take on Fiji.