The left-back has missed the Pirates' last two matches - against Peterborough and Yeovil - through suspension after receiving 10 yellow cards this term.
But, with his return beckoning, Sawyer has sustained a knock in training and will not be considered for selection.
Otherwise, caretaker boss Stuart Campbell has no fresh injury or suspension concerns.
That means Campbell is likely to pick an unchanged starting XI after Rovers secured a hard-fought 1-0 victory over Yeovil on Saturday.
The Pirates remain in the relegation zone but are just one point adrift of safety.
Source: PA
Source: PA