Although the Vikings have said they hope Frerotte will be able to play, Taylor said during an interview with WCCO-TV in Minneapolis that a decision has already been made to start Jackson because Frerotte is suffering from a lower back injury.
Jackson has not started since being replaced following Minnesota's second straight loss to open the season on Sept. 14. However, he looked solid in leading the team on a game-winning drive last Sunday against Detroit after Frerotte got hurt.
Frerotte, a 15-year veteran who came to Minnesota in free agency this year, has helped the Vikings to an 8-5 record and a one-game lead in the NFC North.
A loss by Chicago Thursday night against New Orleans and a win by Minnesota against Arizona Sunday would give the Vikings the division title and their first playoff berth in four years.