Piers Francis could be punished for his hit on Will Hooley during England's win against the USA in Kobe on Thursday.
The Saints centre has been cited for the tackle he made inside the opening 10 seconds of the World Cup clash.
Francis did try to wrap but his shoulder made contact with the head of Hooley.
And the England man now faces an anxious wait to see if he will be suspended.
If the citing is upheld, Francis is facing a ban in the region of six weeks minus any reduction for mitigating circumstances, potentially ending his involvement in Japan 2019.
On the basis of the outcome of citings for similar offences already at this World Cup, the Saints playmaker would appear to be looking a mid-range sanction of a six-week suspension reduced to three.
When asked about whether Francis should have been punished during the game, England boss Eddie Jones said: "We leave that up to the referee.
"We're quite happy whatever the judicial process is to take part in it.
"We've got no qualms one way or the other.
"Whatever way it goes, we'll support the decision by World Rugby."