The Vikings have added veteran quarterback Josh Dobbs. For now, however, they plan to ride with a rookie.
On Sunday and Monday, O'Connell had not been prepared to commit to Hall.
A fifth-round pick from BYU, Hall finished Sunday's game against the Packers after Kirk Cousins left with a torn Achilles tendon. Hall completed three of four passes for 23 yards. He also fumbled on a sack, losing possession to Green Bay.
If the Vikings play well against the Falcons, it will be interesting to see whether Hall keeps the job. Especially with receiver Justin Jefferson eligible after Sunday to return from injured reserve.