The Saracens second row suffered an eye injury in a club match at the weekend and is expected to be out of action for between two and four weeks.
If the later prognosis proves more realistic, then Borthwick will only have a week to prove his match fitness before England face Australia at Twickenham on November 7.
It is the second injury scare for the former Bath star in as many weeks after he sprained a rib cartilage in the comfortable victory at Harlequins.
Having been cleared to play following that initial setback, Borthwick lasted less than a quarter of yesterday's match and was later given five stitches at a specialist eye unit.
The 29-year-old appears to have been involved in an incident with Gloucester hooker Olivier Azam during Sarries' 19-16 win at Vicarage Road on Sunday - with Sarries coach Mark McCall particularly critical of the Gloucester player.
"We are concerned at the way it occurred and it would appear it may have been a deliberate act of foul play," said McCall when discussing the incident which took place at a ruck with just 13 minutes played.
"It is more than a cut. His eye is completely closed over and at this stage we don't know how badly damaged it is.
"The video footage we have seen so far would appear to be reasonably clear.
"It is something nobody wants to see. Steve was on the ground and pretty much defenceless."
Azam, on the otherhand, has protested his innocence, claiming that if he made any contact with his opponent, it was purely by chance.
"I didn't know I did it," said the Frenchman.
"I did not know I had made contact with Borthwick's head.
"All I remember is someone grabbing my ankle at the ruck when I was in the floor but I do not recall making contact with anyone and, if there was contact, it was an accident."
Borthwick will see a specialist later today to assess the full extent of his injury.