Billy Vunipola will find out on Tuesday if his ankle injury will prevent him confronting France in their World Cup Pool C decider.
The Saracens No 8 didnt appear in the weekend for the second half of England victory over Argentina.
Vunipola is the only player to have started all 12 of Englands matches with his staff and Eddie Jones expecting he is going to be available to carry in Yokohama on France.
Billy has just had a scan and well get a clearer picture elsewhere [Tuesday], said scrum coach Neal Hatley.
Hes being examined, that will proceed throughout the afternoon and then we will see how he pops up. Hes another 24 hours and then well make a firm identification.
If Vunipola isnt passed fit, then Mark Wilson or Tom Curry will deputise at the row, but his lack will have a significant influence on Englands ball carrying.
Billys brother Mako left his comeback and would help fill the void, however, Hatley insists there are other choices.
We aim for all eventualities and with what we have in Ellis Genge, Mako Vunipola, Maro Itoje, Courtney Lawes and Kyle Sinckler, there are people to pick up the slack if Mako and Billy dont play, added Hatley.
Weve played a great deal of rugby without them. Billy is a significant figure for us, but other folks pick up the slack.