England fly-half George Ford suffered a torn thigh muscle during Sale’s 45-26 Gallagher Premiership defeat to Saracens.
And in another concern for England head coach Steve Borthwick ahead of the autumn Tests, Northampton scrum-half Alex Mitchell remains sidelined with a neck problem that has delayed his start to the season.
Ford underwent a scan on Monday evening after being forced off inside seven minutes of Saturday’s game at StoneX Stadium.
Sharks director of rugby Alex Sanderson is awaiting a full diagnosis to determine how long the playmaker will be sidelined.
England begin their four autumn internationals on Saturday, November 2 when New Zealand visit Twickenham.
“Just the initial reports from the scan, it is a tear,” said Sanderson. “It was definitely the right thing to bring him off.
“We don’t know the length of time that will take to rehab at this point. We haven’t got anything definite or concrete to tell you now.
“He’s important to us, King and country. Nationally important, he is.
“I can perceive (him) being back (after) not an overly-long layoff given how he walked off the field but that’s the only subjective analysis I’ve got on it.”
Ford missed his country’s summer tour of Japan and New Zealand with a damaged Achilles.
He left the pitch against Sarries soon after attempting a long-range penalty.
The 31-year-old, whose existing Sale contract expires at the end of the season, is in talks over extending his deal to the 2027 Rugby World Cup, with Sanderson confident of reaching an agreement.
“It’s up for renewal at Christmas and we are in negotiation for extending to the World Cup – positive tones, I might add,” said Sanderson.
On England number nine Mitchell, Northampton rugby director Phil Dowson said: “He’s had scans, he’s had some treatment and we’re just waiting to see if that treatment is sufficient to get him going again.
“It’s wait and see at the moment. There is genuinely no timeline, because it could be anything at the moment.
“It’s up in the air so it’s hard to make a short-term plan or a long-term plan when you don’t have that information.
“But he’s feeling a bit better on the back of some time off.
“I think he’s probably bored more than anything else, but he’s also a bit frustrated because there’s no timeline to work to.
“He came in one morning and he had a very sore neck. We obviously had the specialist look at it, and what you don’t want to do is mess around with it.”
Sale, meanwhile, who host Gloucester on Friday evening, remain uncertain when England lock Jonny Hill will be back in contention for selection.
Hill is still awaiting the outcome of a police investigation sparked by his reported altercation with a Bath fan in June.
“We have no clarity on Jonny with regards to the exact date he’s going to return because it’s still with the authorities at the moment,” said Sanderson.
“I have to take deep breaths and accept that it’s out of my control and out of Jonny’s at this moment in time.
“It’s not like we’re not chasing it up. We’ve got barristers on the case and have had since the start of this. It’s just a long process that is not conducive to professional sport.”