Harris (ankle) wasn't spotted on the field during the media-access portion of Friday's practice, Zack Cox of NESN.com reports.
The 23-year-old was a limited participant at practice Wednesday, but his potential absence at Friday's session after missing the past two games is an ominous sign for his availability this weekend against the Jets. Sony Michel, James White and J.J. Taylor will again handle backfield duties if Harris is ruled out ahead of Sunday.