Bears coach Matt Eberflus said quarterback Justin Fields’ dislocated thumb on his throwing hand likely will keep him out of the game against the Raiders on Sunday. That means backup Tyson Bagent would start Sunday against the Raiders.

“There’s no timetable right now,” Eberflus said of Fields’ return. “We should know more by the end of the week.”

Fields hurt his thumb early in the fourth quarter of the Bears’ 19-13 loss to the Vikings on Sunday and was replaced by Bagent.

Bagent, 23, is an undrafted rookie from Division II Shepherd University who made his NFL debut Sunday. He completed 10 of 14 passes for 83 yards with an interception and a one-yard touchdown run.

Fields completed 6 of 10 passes for 58 yards with one interception and no touchdowns for a 36.7 passer rating before getting hurt.

For the season, Fields is averaging 200.2 passing yards, completing 61.7% of his passes and has 11 touchdown passes against six interceptions for a 91.6 passer rating.