The Republic of Ireland international picked up a knee injury in the draw at Peterborough but is expected to be fit in time to face Nottingham Forest at the weekend.
Nathan Dyer, who came off the bench for Butler shortly after the hour mark at London Road, should replace him in the starting line-up.
Craig Beattie is the only other new injury worry and the striker faces a late fitness test.
Captain Garry Monk is still sidelined with a calf injury but fellow defender Alan Tate returns after serving his one-match suspension for picking up five bookings.
Striker Stephen Dobbie (ankle) and midfielder Mark Gower (hamstring) are also still out.