"Maro came off with a sore hand,” said the Saracens director of rugby, Mark McCall. "He will be examined and have an x-ray after which we will know more."
Saracens are due to give an update on Monday.
Should Itoje be ruled out of the series, which opens against South Africa at Twickenham on Nov. 12, it will be another blow to coach Eddie Jones who has already seen four flankers, second row George Kruis and several backs, including Manu Tuilagi ruled out.
Itoje had been touted to move from lock, where England are well served with replacements, to the problem area of flanker following the injuries to James Haskell, Jack Clifford, Mike Williams and Sam Jones.
In the autumn series, England also play Fiji on Nov. 19, Argentina on Nov. 29 and Australia on Dec. 3.
(Reporting by Neil Robinson, editing by Pritha Sarkar)
