The Pirates have won six of their last eight games and are five points off a play-off place, and three behind the Bantams, with four games left to play.
But John Ward's men will go into pivotal encounter without their captain as Parkes serves the second game of his two-match ban after accumulating 10 yellow cards during the campaign.
Loanee Clayton McDonald was handed a full debut in Parkes' place on Saturday as Rovers beat AFC Wimbledon 1-0, and is expected to continue in defence.
Winger Ellis Harrison was withdrawn at the weekend after suffering a dead leg but is expected to shake off the knock to keep his place in the starting XI.
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