Winger Green completes his three-match suspension while fellow midfielder Gain starts a three-game ban of his own after his dismissal against Oldham last week.
Gain is likely to be replaced by Solomon Taiwo who is fit again, so Still will revert to a 4-4-2 formation with Darren Currie coming in for Billy Bingham.
Striker John Akinde joined on loan from Bristol City last month but has not even trained with his new side as he battles a groin injury.
He has now returned to Ashton Gate to receive treatment as he hopes to avoid surgery on the problem.
Fellow striker Josh Scott has been struggling with a mystery illness and was diagnosed with a blood clot this week which has ruled him out for the rest of the season.
Source: PA
Source: PA