McDonald kicked one goal from six disposals against the Magpies and has been named as one of the Swans' four emergencies.
It's likely that McDonald would come back into the starting side if Reid is unable to prove his fitness.
Not since Hawthorn replaced Jon Ceglar with Ben McEvoy for the 2014 Grand Final has a player been omitted for the season decider based on form, having played the previous week.
10:09MINS Match Preview GF: Geelong v Sydney
Sportsbet's Nathan Brown, Brendon Goddard and Matthew Richardson preview the Grand Final between the Cats and Swans at the MCG.
Published 8 hrs ago
Geelong is unchanged from the team that walloped the Lions, but has a host of possible replacements to call on should Holmes be a late scratching.
Mark O'Connor, Sam Menegola and Brandan Parfitt are all emergencies.
Saturday, September 24 Geelong v Sydney at the MCG, 2.30pm AEST
In: Nil Out: M.O'Connor (Medi-Sub)
Preliminary final sub: M.O'Connor (replaced M.Holmes in the third quarter)