Falcons rugby director Steve Bates said: "Jonny suffered a bit of a concussion against London Irish last weekend and the medical staff were keen for him to have a rest.
"He hasn't trained this week, and it just makes sense from our point of view not to rush him back when we know we need him 100 per cent fit for our European Challenge Cup semi-final next Friday.
"Likewise, Jamie and Toby, who are both getting a lot better after recent ankle injuries.
"This weekend just came a bit too soon for them, but they are both running around in rehab and we hope to have them back fit next week.
"The quality of opposition means this will be a very tough game and Sale will pose a lot of questions, but it is our players' responsibility to exploit this opportunity.
"I am confident we can create opportunities, and I am expecting guys to step up.
"They won't find it easy against a team like Sale, but selection is still open for next Friday, and if players put their hands up on Sunday, they stand every chance of being in that team for Worcester."