SANTA CLARA, Calif. • The Broncos offense got off to a bad start. So did the defense. And so did the special teams.

On the scoreboard, it didn’t end up mattering as Denver defeated the San Francisco 49ers 30-9 in the preseason opener Saturday night at Levi’s Stadium.

After falling behind 9-0, the Broncos scored 20 straight points to close the first half. They got touchdown passes from backup quarterback Jarrett Stidham of 8 yards to Lucas Krull and 36 yards to Trent Sherfield during that run. They went up 23-9 in the third quarter on Wil Lutz’s third field goal of the game and 30-9 on a 7-yard touchdown pass from Sam Ehlinger to Caden Prieskorn with 2:15 remaining.

But the start of the game didn’t go the way the Broncos had hoped. The 49ers, who rested starters, waltzed 71 yards down the field on their first possession for a 5-yard touchdown run by Patrick Taylor Jr. against Denver’s vaunted defense.

The Broncos on offense didn’t score on their first two possessions. And when Bo Nix was called for intentional grounding in the end zone on their second possession, the 49ers took a 9-0 lead.

Throw in also the Broncos on special teams allowing San Francisco’s Junior Bergen to have a 28-yard punt return in the first quarter.

Eventually things started coming together for the Broncos. On their second defensive possession, outside linebacker Nik Bonitto had two sacks of 49ers quarterback Matt Jones and nearly a third. On the next defensive possession, with reserves in the game, Ja’Quan McMillian had an interception, the first of four Denver takeaways.

That interception led to the Broncos on their third offensive possession, with Nix still in the game, getting a 42-yard field goal by Lutz to cut the deficit to 9-3. Nix had an unimpressive night, completing 6 of 11 passes for 31 yards for a 60.0 passer rating.

“There will be a lot of film to cover, not even from just the game but also we’re going back to the (joint) practice we had (Thursday with the 49ers),’’ Broncos coach Sean Payton said. “I thought we started slow. That was disappointing. Both first units. So, they’ll be a handful of stuff we look at there. … Then things began to pick up. Jarrett did a good job. Defensively, we ended up with four takeaways. Too many penalties (11) for my liking. … I’ve got 14 things written down that I’m pissed off about that have nothing to do with the game.”

As for the game, Payton said the intentional grounding call “would be” a teaching point for Nix, who was under heavy pressure from cornerback Chase Lucas before throwing the ball away just inside the goal line. The quarterback downplayed his tough night as well as the safety.

“I just didn’t quite look at the line of scrimmage to get the ball there,’’ Nix said.

There was little to complain about when it came to the Broncos’ reserves. Stidham, playing through the third quarter, completed 14 of 15 passes for 136 yards and two touchdowns with a 144.0 passer rating and also rushed three times for a team-high 36 yards.

“It was good that we were able to move the ball and put some points on the board,’’ Stidham said. “But the guys around me played great. The O-line played incredible. The backs ran the ball super well and that obviously helps the pass game. And the receivers were running a lot of good routes and catching the football.”

Plenty of eyes were on the Broncos’ running backs entering the game. Rookie RJ Harvey started over veteran J.K. Dobbins and had seven carries for 25 yards. Dobbins didn’t have an attempt in limited action but had one catch for four yards.

Tyler Badie led Denver’s running backs with 32 yards on five carries and Blake Watson had three carries for 25 yards. Reserve Jaleel McLaughlin had three carries for five yards and Audric Estime had nine attempts for 24 yards.

“We divided it into how we were going to play (running backs),’’ Payton said. “(Harvey) will continue to work with the ones (along with Dobbins)…. We’re trying to build cases to all (of the running backs), keep giving all these opportunities so the decision can become a little bit easier. It’s difficult right now.”

Among the receivers, Sherfield and Troy Franklin each had three catches. Sherfield had 73 yards receiving, his touchdown coming on a diving catch at the right pylon.

“Just grateful to have that opportunity to compete here and to be able to try to showcase those things,” Sherfield, who is a special teams ace, said of wanting to be a complete player.

Not playing for the Broncos on Saturday were linebackers Alex Singleton (thumb), Dre Greenlaw (quad) and Drew Sanders (foot), defensive lineman Matt Henningsen (torn Achilles), tight end Nate Adkins (undisclosed), fullback Michael Burton (undisclosed) cornerback Reese Taylor (undisclosed) and wide receiver A.T. Perry, on the physically unable to perform list with an undisclosed injury. Payton said after the game that Henningsen, who was hurt in the joint practice, will have surgery and is out for the season.

The Broncos used their healthy starters. Brandon Jones started at safety after sitting out Thursday’s joint practice against the 49ers. With Singleton and Greenlaw out, the starting linebackers were Justin Strnad and Levelle Bailey.