Justin Fields isn't upset that most football observers outside Halas Hall don't think the Bears will beat the Packers Sunday night. In fact, he embraces the situation.

"I like being the underdog," said the rookie quarterback, who was rarely in that role at Ohio State. "It just gives me an extra chip on my shoulder. I like when people doubt me. That just gives me a little extra motivation, so I love it."

After missing the last two games due to cracked ribs, Fields was medically cleared early in the week and is expected to start Sunday night's game.

The first-round pick understands why the 9-3 Packers are heavily favored over the 4-8 Bears. But that won't dilute his determination to topple the NFC North leaders.

"I just think a lot of the times, teams maybe don't respect us or give us credit," Fields said. "I mean, you can't blame them. We've pretty much messed up in a lot of games. So, I mean, that's fine. We're going to attack every game like it's our last game and we're going to play through it all."

Changing plans: Offensive coordinator Bill Lazor revealed Thursday how his game-planning changes depending on whether Fields or veteran Andy Dalton is going to start.

"I'll use the list of pass plays as an example," Lazor said. "When you study the team you're playing, certain plays on that list get highlighted: 'Hey, these are good against this team.' And our players already know them, so we don't have to make up something new this week, for these plays.

"Then the next level is, which of these do we as coaches think Andy is really comfortable [with] versus where's Justin real comfortable? So, it's the same offense. [But] you've got to be smart: 'Have we seen this guy be really good with this play? What are the plays that are his best?'

"And some of it is talking to them. We're taking in their feedback during the week, at the end of the week: 'Here is our third-down list. How do you feel these have gone this week? Do you have an order? Do you have a priority?'

"We have a long list. [We ask], "Is there something on here that you just don't like?' Trust me, we will cross it off. There is no one play we have to have."

Injury update: Running back David Montgomery was limited in practice Thursday after sitting out Wednesday with injuries to his shoulder, groin and glute.

Defensive end Mario Edwards Jr. (ribs) and linebacker Christian Jones (back) were full participants after being limited Wednesday. Kicker Cairo Santos also practiced without restrictions after sitting out Wednesday with an illness.

For the second straight day, Dalton (left hand) and outside linebacker Trevis Gipson (illness) did not practice; and receiver Allen Robinson II (hamstring), running back Damien Williams (calf) and defensive tackle Akiem Hicks (ankle) were limited.

Receiver Marquise Goodwin (foot) did not practice after being limited Wednesday.

Frozen tundra: Robinson enjoys playing in historic Lambeau Field.

"It's always a great environment and atmosphere," he said. "I will say it is a little bit more fun playing there in September, but the atmosphere is always great. The fans come, it's exciting, they're loud.

"When you're growing up and you see games at Lambeau, you watch these games, Chicago Bears versus Packers, or for me growing up living in Detroit, seeing Green Bay vs. Minnesota and Randy Moss and Charles Woodson and all those guys. It's the same atmosphere that you kind of would envision from being a kid until now."