Arnason completes a two-match ban for his red card in last week's damaging home defeat to Dagenham while right-back Mark Bradley is out for the season with a cracked bone in his foot.
Both men missed Tuesday's 2-2 draw at Wycombe and boss Steve Evans may stick with the back four that played at Adams Park or bring Craig Morgan into a central berth and move Johnny Mullins back to right-back.
Elsewhere, Daniel Kearns could be pushing for a start on the wing following his comeback from a hamstring injury, though Evans is likely to stick with his front six.
Former Millers midfielder Jason Taylor, who signed for the Robins in January, is not expected to play following a gentleman's agreement between the two clubs.
The Millers are in fifth position, three points off the automatic promotion places and with nine games to go, any finish in the top seven is a possibility.
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- Steve Evans
- Mark Bradley