Northants head coach David Ripley has revealed Muhammad Azharullah is set for a lengthy spell on the sidelines after sustaining a shoulder injury.
Azharullah, a T20 specialist for the Steelbacks, missed the opening fixture of the NatWest T20 Blast on Friday night.
Northants, who won the competition last year, were beaten by seven wickets at the County Ground as Derbyshire Falcons got off to a flyer.
And after the match, Ripley confirmed that Azharullah would not be available for the foreseeable future.
"Azhar will be a bit of a longer term injury - he's not going to be around for a while," Ripley said.
"He's got a shoulder injury. There's a bit of a tear at the back of his shoulder.
"He's had the scan and it wasn't very good news, but he's seen the specialist and it wasn't quite so negative.
"We might end up with somewhere between the two, which could mean he's out for quite a few weeks."
Big-hitting South African batsman Richard Levi is also set to miss Sunday's trip to Durham due to the concussion he initially sustained in a Championship match against Worcestershire in May.
But he could return for the home clash with Yorkshire on Tuesday night.
"Richard Levi probably won't make Sunday, but we hope he will be back by Tuesday," Ripley said.
"He's still ticking off some of the concussion things.
"He's got to go through that protocol.
"He got another glancing blow on the head in the second 11 game and that's set him back a bit.
"It's unfortunate, but there's nothing we can do about that.
"It will be good to get Rich back when he's fit and ready."