Head coach Kyle Shanahan said Wednesday that Dobbs will start Sunday's game at Arizona, Nick Wagoner of ESPN.com reports.

EDGE Analysis

Dobbs served as the 49ers' backup quarterback over Brandon Allen in Monday's 40-34 loss to the Lions, and the former saw the field late in the fourth quarter when Brock Purdy exited with an elbow injury. Dobbs proceeded to complete three of four passes for 35 yards and ran for a seven-yard touchdown on his five snaps. Purdy since has been diagnosed with a contusion and nerve inflammation in his throwing elbow, which is expected to sideline him for Week 18 action. Dobbs thus is in line for his first start of the campaign as the 49ers close out the season.