And both defenders could be sidelined for a few weeks after sustaining injuries at home to Inverness at the weekend.
Wright left the field in the 38th minute after damaging ankle ligaments while Scobbie - who replaced him - also suffered a knock and will require a scan.
Steven MacLean is close to a comeback following knee surgery but midfielder Murray Davidson is out for the season.
Meanwhile, Motherwell have an unchanged squad for their trip to Perth.
Fraser Kerr has returned to training following an ankle injury but will not be fit enough to face the Saints.
Also absent, due to injuries, are Simon Ramsden, Lee Hollis, Craig Moore and Paul Lawson.
Keith Lasley and Stuart Carswell are expected to start despite niggles while Henri Anier requires a scan on a shin problem.