Chadwick has not started a game since the opening day of the season but the experienced former Manchester United winger is expected to return to the team on Saturday.
Ben Reeves will not feature due to an injury which forced him out of the starting XI last weekend. The midfielder, who played at left-back in the home win over Crewe, was deemed fit enough for the bench at Preston but he will miss the Robins game.
Captain Dean Lewington (knee) and forwards Dean Bowditch (groin) and Daniel Powell (ankle) will remain on the sidelines. Lewington, whose troublesome injury has limited him to just one appearance this season, took part in light training on Thursday but the Sky Bet League One fixture will come too soon for him to be considered.