Khalil Mack enjoyed Sunday's reunion with the Raiders much more than they did, spearheading a dominant defensive effort that helped propel the Bears to a stirring 20-9 win at Allegiant Stadium in Las Vegas.

Obtained by the Bears in a blockbuster trade with the Raiders days before the start of the 2018 season, Mack produced impact plays throughout Sunday's contest. In the first half, he drew a holding penalty that nullified Josh Jacobs' 2-yard touchdown run, stuffed Jacobs for no gain on fourth-and-1 and sacked close friend and former teammate Derek Carr.

Mack later sacked Carr again on a two-point conversion attempt, preventing the Raiders from closing to within 14-11 with 9:01 left in the fourth quarter. Mack won't be credited with a sack because it came on a conversion try, but it nonetheless was a huge play in the game.

"Oh man, it was amazing," safety Eddie Jackson said of Mack's performance. "He made them regret everything, made them regret not wanting to keep him. Mack's our leader. He's had games like this. We fuel off that. Just to see him and come back here and dominate, it's a great feeling."

Stepping up: With running back David Montgomery placed on injured reserve Saturday due to a sprained knee, veteran Damien Williams and rookie sixth-round pick Khalil Herbert more than filled the void.

Herbert rushed for a game-high 75 yards on 18 carries, while Williams added 64 yards on 16 attempts, including a 4-yard touchdown that gave the Bears a 14-3 lead with 1:56 remaining in the first half.

"When you have a guy like David who is a run-hard kind of guy and he's going to get those hard yards, that's what everyone is expecting," Williams said. "And me being who I am, that's how I carry myself as well. We are going to go in there and get these hard yards and keep going. And '24' (Herbert) had that same mentality, so whenever I went out and he went in, we kept doing the same thing."

Both backs benefited from strong blocking by the offensive line as well as receivers and tight ends.

"It talks a lot to the offensive line and tight ends," coach Matt Nagy told reporters. "It talks a lot to those running backs. It talks a lot to our coaches for getting those guys ready. I think you guys would probably agree there's a little bit of an identity going on right now. That's real.

"When you have that running game it certainly makes things a lot easier in a lot of different ways."

Toughness personified: Rookie quarterback Justin Fields showed his toughness Sunday, taking several crushing hits and even leaving the game briefly after being sacked by defensive end Yannick Ngakoue with 5:56 left in the second quarter. Fields returned after missing only three plays.

"I knew I hyperextended it," Fields said. "I was just trying to see if I could get up, and I was just able to walk off the field and then after a while I could start feeling my strength getting back, so I was just trying to see how stable it was and seeing if I could run on it."

Fields completed 12 of 20 passes for 111 yards and one touchdown with a 91.9 passer rating. His first NFL TD pass came on a 2-yarder to @Jesper Horsted that gave the Bears a 7-3 lead early in the second quarter.

Another impressive Fields throw resulted in a 13-yard completion to Darnell Mooney on third-and-12 from the Bears' 27, sustaining a drive with 6:45 left in the game after the Raiders had just closed the gap to 14-9.

Playing takeaway: Safety DeAndre Houston-Carson produced the game's only takeaway, intercepting a Carr pass intended for receiver Zay Jones at the Bears' 45 with 11:01 to play in the third quarter.

It was the second career interception for Houston-Carson, a 2016 sixth-round draft pick who is in his sixth season with the Bears. His first pick came last Oct. 18, preserving a road win over the Panthers.

"The guy works his tail off each and every week," said linebacker Roquan Smith. "I don't know anyone that works harder than '36,' and, man, I've got a lot of respect for the guy as a player and as a person. So, I'm very excited and very happy that the guy was able to make some plays out there."

Still streaking: Cairo Santos made the only two field goals he attempted Sunday, both from 46 yards in the fourth quarter. His first gave the Bears a 17-9 lead with 2:45 to play and his second iced the game with :56 remaining.

Santos has now made a Bears-record 34 straight field goals, the NFL's longest active streak.

On the shelf: In addition to Montgomery, the Bears played without tight ends Jesse James (personal reasons) and J.P. Holtz (quad), defensive tackle Akiem Hicks (groin) and linebacker Joel Iyiegbuniwe (hamstring). Other inactives were quarterback Nick Foles and receiver Breshad Perriman.

Injured in game: Right tackle Germain Ifedi and reserve linebacker Caleb Johnson exited Sunday's game with knee injuries. Ifedi was replaced by Elijah Wilkinson. Outside linebacker Jeremiah Attaochu left with a pectoral injury.