49ers pregame: Trent Brown, Adrian Colbert back in the lineup

Trent Brown is back at his familiar right-tackle spot after missing last week’s game with a shoulder injury.

His return means quarterback Jimmy Garoppolo will work behind the 49ers’ top offensive line today in his first start for the 49ers and just his third-ever NFL start. The 49ers have allowed 35 sacks this season, tied for sixth-most in the NFL.

Zane Beadles will be the backup at guard and center; rookie Darrell Williams Jr. will serve as the emergency tackle.

Along with Brown, safety Adrian Colbert is active after missing last game with a broken thumb. Colbert presumably start at free safety because the player who stepped in for him last week, Antone Exum, is inactive. Cornerback Ahkello Witherspoon, who tweaked his ankle in Wednesday’s practice, also is active.

Along the defensive line, three defensive ends -- Aron Lynch, Tank Carradine and Pita Taumoepenu -- are inactive. The active ends include Solomon Thomas, Ronald Blair, Leger Douzable and newcomer Cassius Marsh.

At running back, Jeremy McNichols was elevated from the practice squad early in the week after Raheem Moster was placed on injured reserve. McNichols, however, is inactive today, which leaves San Francisco with just Carlos Hyde and Matt Breida at the position.

49ers inactives:

RB Jeremy McNichols

DB Antone Exum Jr.

DE Pita Taumoepenu

DE Aaron Lynch

OL Tim Barnes

NT D.J. Jones

DE Tank Carradine

Bears inactives

QB Mark Sanchez

SS Deon Bush

DB DeAndre Houston-Carson

DB Adrian Amos

RB Taquan Mizzell

CB Bryce Callahan

C Hroniss Grasu.

This story was originally published December 3, 2017 at 8:41 AM.