Tebow has taken nearly every snap this week in practice with starter Kyle Orton nursing bruised ribs. The Broncos' plan to start Tebow is based on his talents, the source said.
Tebow has made only cameo appearances this season and thrown just one NFL pass.
The Packers said Matt Flynn will get his first career NFL start after Rodgers suffered his second concussion of the season.
Vikings interim coach Leslie Frazier said Favre tried to "do some things prior to practice, but the shoulder, the arm is not quite where it needs to be."