Farmer was recalled from Triple-A Toledo on Sunday.
Though the Tigers and White Sox aren't technically playing a doubleheader Sunday, both teams will be allowed to carry 26 men since the two sides have to first conclude Saturday's game, which was postponed in the ninth inning due to rain with the score tied at 3-3. The single game originally scheduled for Sunday will be played immediately after the postponed game is completed, but Farmer is eligible to pitch in either contest. He'll likely be sent back down to Toledo immediately after Sunday's games are completed.