Harris (thigh) wasn't spotted at practice Thursday, Evan Lazar of the Patriots' official site reports.
Harris logged a limited practice Wednesday, so his reported absence Thursday is notable. What he's able to do Friday will be pivotal with regard to his chances of playing Sunday against the Dolphins, but if Harris remains sidelined this weekend, Rhamondre Stevenson (ankle, limited Wednesday) would presumably be in line to continue to lead the Patriots' backfield Week 17.