Thornton (undisclosed) wasn't in uniform ahead of Saturday's preseason contest against the Packers, Evan Lazar of the Patriots' official site reports.
Thornton exited practice early Thursday and didn't return, so his absence isn't much of a surprise. The 2022 second-rounder will need to get back on the field soon in order to secure a key Week 1 role in a Patriots WR corps that also features JuJu Smith-Schuster, DeVante Parker and Kendrick Bourne.