LAKE FOREST, Ill. (AP) — Bears quarterback Justin Fields is not expected to need surgery for his dislocated right thumb, coach Matt Eberflus said Friday.

As expected, Fields was ruled out for Sunday’s game against the visiting Las Vegas Raiders (3-3). Undrafted rookie Tyson Bagent will start for Chicago (1-5).

It appears that Fields, at least for now, will avoid injured reserve, Eberflus said.

“The mobility’s getting better, the swelling went down, the grip strength is better,” Eberflus said. “It’s trending in the right direction. He’ll be week to week and we’ll know more Monday. That’s where it is right now with Justin.”

Fields needs to be able to achieve specific benchmarks in his recovery before returning.

“Improvement, more improvement, more mobility, more swelling going down,” Eberflus said. “And then see him … the grip strength is really where it is, the functionality of it. If we see more of that, and it’s obviously trending in the right direction. That’s what it’s done this week. That’s where it’s looking good.”

Bagent went 10 of 14 for 83 yards with an interception and lost fumble in relief of Fields last week in a 19-13 loss to the Minnesota Vikings. He came on in the third quarter for his first NFL appearance after Fields was hurt. The interception sealed the loss for the Bears as Bagent tried to hit DJ Moore in the end zone but threw well short of the mark when he couldn’t follow through while colliding with a teammate.

Offensive coordinator Luke Getsy labeled the pass more of a physical error than a rookie mental mistake.

“If you get one on one with your best guy, you got to let it fly,” Getsy said. “Now he took three hitches and that was his issue. He’s right in the middle of the pocket and he took three hitches. He really ran himself into the left guard.”

Despite the mistake, Getsy believes the former Division II passer from Shepherd University can get the job done.

“He has a lot of confidence and he works his butt off,” Getsy said. “The preparation is what gives him his confidence from the time that I have been around him.”

Getsy had his first exposure to Bagent when he coached the rookie’s Senior Bowl team.

“Like I said in that Senior Bowl week, in the beginning of the week I kinda thought he was a nervous dude, but I think it was because he was working his tail off so much,” Getsy said. “By the time we got to Wednesday, Thursday, I mean, I saw a guy ready to rock and roll.

“So I think he has done that. I think he has just put the work in, he’s proved to the guys and that’s what they feel on the daily.”

The Bears also ruled out safety Eddie Jackson with a foot injury. Jackson initially hurt his foot in Week 2. He returned last week but left the game after 14 plays when he re-injured it.

Starting right tackle Darnell Wright and safety Jaquan Brisker were questionable. Brisker has a groin injury but Wright’s chances to play Sunday improved greatly after he went through a full practice on Friday. He sat out Thursday.