Brown has seen a specialist about his abductor problem and will discover on Monday if he requires surgery while Lustig is out with a thigh injury.
Defender Charlie Mulgrew is a doubt with a glute problem.
Motherwell will be without defender Fraser Kerr after he missed the weekend defeat to Ross County through illness and remains out of action.
Fellow defender Zaine Francis-Angol is a doubt after being forced out of Saturday's match.
Midfielder Tom Hateley and defender Steven Hammell both missed the clash with the Highlanders and McCall hopes one of them could be passed fit for the visit of the Hoops.