Harris leads the team with 691 rushing yards on 137 attempts, with two touchdowns.
He had injured his back in the fourth quarter of a Week 14 loss to the Los Angeles Rams, but ultimately was deemed healthy earlier this week and wasn't on the injury report Wednesday when the Patriots held their initial practice to prepare for the Dolphins.
Harris, however, was added to the injury report the next day because of his ankle, opening the door for former No. 1 back Sony Michel to elevate back to the top spot.
Patriots running backs coach Ivan Fears said on Dec. 11 that Michel would be ready if the opportunity presented itself.
"He's a real team player. He knows Damien is really playing well, and Sony is sort of waiting for an opportunity to show what he can do," Fears said at the time. "He always practices hard and is the kind of guy you love having around and can depend on. I'm very fortunate. No matter who goes down, I know I have great players who can step in and keep us on track."
The Patriots (6-7) are clinging to long-shot playoff hopes, with ESPN's Football Power Index giving them a 3% chance to qualify.
The Patriots also ruled out top kickoff returner Donte Moncrief (thigh) for Sunday's game.