Weatherspoon, 25, was set to undergo an MRI on Monday.
The third-year linebacker out of Missouri made six tackles (five solo) in Sunday's game before he was injured in the fourth quarter. He did not return to the game.
Of Weatherspoon's injury, Pro Football Talk's Mike Florio said, "It's believed for now that he'll be OK, and that the ankle sprain is only minor."
Defensive tackle Vance Walker left with a head injury, but returned to action.
Defensive tackle Corey Peters, who was activated from the reserve/non-football list on Friday, made his season debut in the second quarter.
Garrett Reynolds missed Sunday's game because of a back injury. In his place, Atlanta started top draft pick Peter Konz at right guard.