The Denver Broncos overpowered the largely reserve-filled San Francisco 49ers 30-9 in Saturday night’s preseason opener at Levi’s Stadium, erasing an early nine-point deficit behind a pair of second-quarter touchdown passes from backup quarterback Jarrett Stidham. Head coach Sean Payton kept most of Denver’s starters on the field for three series, but second-year quarterback Bo Nix managed only 56 yards on 18 snaps before giving way to Stidham. The veteran immediately exploited San Francisco’s backup secondary, hitting tight end Lucas Krull from five yards and receiver Trent Sherfield on a 36-yard strike to put the Broncos firmly ahead by halftime. San Francisco, resting Brock Purdy and nearly all front-line players, struck first when new No. 2 quarterback Mac Jones found rookie Jordan Watkins for a 50-yard gain that set up Patrick Taylor Jr.’s five-yard touchdown run. Cornerback Chase Lucas briefly extended the lead to 9-0 with a nickel blitz that forced Nix into an intentional-grounding safety, but the 49ers’ offense stalled thereafter; Jones finished 4-of-7 with one interception, and reserves Carter Bradley and Tanner Mordecai failed to sustain drives. Rookies nonetheless supplied bright spots for the 49ers. Watkins added a second catch and drew praise from coach Kyle Shanahan despite a route error that led to the Jones interception. Safety Marques Sigle recorded a team-high seven tackles before exiting with what the club described as a knee bruise. Depth concerns deepened in the backfield after Ameer Abdullah left with a rib injury, one day after San Francisco re-signed running back Ke’Shawn Vaughn and waived offensive lineman Zack Johnson. Linebacker Tatum Bethune (ankle) also departed. Both teams return to joint-practice settings next week, with Denver hosting Arizona and San Francisco traveling to Las Vegas.