It took about 38 minutes of game time, two hours into the night, before Denver fans started booing Trevor Siemian. The Broncos’ newest starting quarterback walked into a rude NFL welcome Thursday.

Even Peyton Manning, a likely hall of famer, was booed by Broncos fans last season. And he eventually won the Super Bowl. But in their first game since that championship run, the first since Manning retired, only seven months later, the Broncos struggled to find a lane for Siemian to cruise.

And Denver fans booed. Just like they booed Jake Plummer and Brian Griese and Jay Cutler and Kyle Orton and Tim Tebow and every passer since John Elway. It’s a rite of passage.

In the end, Siemian, in his first career start, went from jeered to cheered. He shook off a rough first half and threw for 178 yards on 18-of-26 passing to outduel Carolina’s Cam Newton in the Broncos’ come-from-behind 21-20 victory at Sports Authority Field at Mile High.

“We knew we’d have our hands full,” Siemian said. “And it would come down to the wire against these guys. That’s how a lot of games in the NFL work out.”

Siemian’s welcome to the club came in the third quarter Thursday, with the Broncos trailing Carolina 17-7. His pass on second down to C.J. Anderson went for a 5-yard loss. His pass on third-and-14 to Virgil Green gained only 5 yards. And as the punt team trotted out, Siemian walked off to boos.

He had already thrown two interceptions, one in each quarter, and the Broncos were stalled. The difference between Siemian and Carolina’s Newton seemed stark in the first half. Newton threw for 111 yards and a touchdown through two quarters and was the Panthers’ leading rusher, with 36 more.

John Leyba, The Denver Post Running back C.J. Anderson (22) of the Denver Broncos runs against the Carolina Panthers during the fourth quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post running back C.J. Anderson (22) of the Denver Broncos celebrates his touchdown against the Carolina Panthers with teammate Russell Okung (73) during the fourth quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

Joe Amon, The Denver Post Middle linebacker Todd Davis (51) of the Denver Broncos tackles running back Jonathan Stewart (28) of the Carolina Panthers during the second quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



Joe Amon, The Denver Post Quarterback Cam Newton (1) of the Carolina Panthers shouts at the ref after he took what he believed to be late contact from defensive end Derek Wolfe (95) of the Denver Broncos during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

Young fans flex during the second quarter of action between the Denver Broncos and the Carolina Panthers. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

Helen H. Richardson, The Denver Post Trevor Siemian (13) of the Denver Broncos passes against the Carolina Panthers during the fourth quarter of the Broncos' 21-20 win. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



John Leyba, The Denver post Tight end Virgil Green (85) of the Denver Broncos catches a pass against the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post Von Miller (58) of the Denver Broncos sacks Cam Newton (1) of the Carolina Panthers during the fourth quarter of the Broncos' 21-20 win. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

Joe Amon, The Denver Post Quarterback Trevor Siemian (13) of the Denver Broncos works under center against the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



John Leyba, The Denver post Quarterback Trevor Siemian (13) of the Denver Broncos is tackled by defensive tackle Vernon Butler (92) of the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post Running back C.J. Anderson (22) of the Denver Broncos goes over cornerback James Bradberry (24) of the Carolina Panthers and Kurt Coleman (20) for a touchdown during the fourth quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post Carolina Panthers quarterback Cam Newton lies on the turf after getting hit hard by the Broncos' Darian Stewart and Shaquil Barrett (48) during the fourth quarter of the Broncos' 21-20 win on Sept. 8, 2016.



John Leyba, The Denver post Wide receiver Demaryius Thomas (88) of the Denver Broncos makes a catch over cornerback James Bradberry (24) of the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver post Wide receiver Kelvin Benjamin (13) of the Carolina Panthers is tackled by cornerback Chris Harris (25) of the Denver Broncos, Justin Simmons (31) and Bradley Roby (29) after making a catch during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver post Quarterback Cam Newton (1) of the Carolina Panthers fires a pass against the Denver Broncos during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



John Leyba, The Denver post Inside linebacker Brandon Marshall (54) of the Denver Broncos reaches out to tackle running back Jonathan Stewart (28) of the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

Helen H. Richardson, The Denver Post Fans cheer for the action to begin between the Denver Broncos and the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver post Defensive back Robert McClain (27) of the Carolina Panthers lights up wide receiver Emmanuel Sanders (10) of the Denver Broncos after he makes a catch during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016. (Photo by John Leyba/The Denver Post)



Joe Amon, The Denver Post Quarterback Cam Newton (1) of the Carolina Panthers rolls out as he is pressured by the Denver Broncos defense during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post Head coach Gary Kubiak of the Denver Broncos argues with the referees during the fourth quarter of the Broncos' 21-20 win. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

Joe Amon, The Denver Post Center Matt Paradis (61) of the Denver Broncos loses his helmet while blocking against the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



Joe Amon, The Denver Post Quarterback Trevor Siemian (13) of the Denver Broncos fires a pass as defensive tackle Star Lotulelei (98) of the Carolina Panthers pressures him during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

Denver post file Fans watch the action between the Carolina Panthers and the Denver Broncos during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

Helen H. Richardson, The Denver Post A Denver Broncos fan cheers his team on against the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



Helen H. Richardson, The Denver Post Fans cheer for the action to begin between the Denver Broncos and the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

Helen H. Richardson, The Denver Post Fans stand for the national anthem before the first quarter between the Denver Broncos and the Carolina Panthers. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

Helen H. Richardson, The Denver Post Quarterback Trevor Siemian (13) of the Denver Broncos fires a pass against the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



Helen H. Richardson, The Denver Post The Denver Broncos cheerleaders work the end zone as their squad plays the Carolina Panthers during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

Helen H. Richardson, The Denver Post Miles and Mini Miles hype the crowd up before the start of the first quarter between the Denver Broncos and the Carolina Panthers. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

Helen H. Richardson, The Denver Post The Denver Broncos enter the stadium before the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



Joe Amon, The Denver Post Defensive back Will Parks (34) of the Denver Broncos shouts as he runs onto the field with teammates before the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

Helen H. Richardson, The Denver Post Fans watch the action between the Carolina Panthers and the Denver Broncos during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

Steve Nehf, The Denver Post Denver Broncos fullback Andy Janovich and receiver Cody Latimer tackle Carolina Panthers return man Ted Ginn Jr. in the second quarter at Sports Authority Field at Mile High on Thursday, September 8, 2016.



Helen H. Richardson, The Denver Post A parachuter drops into the stadium near the Denver Broncos logo at midfield before the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post Annabel Bowlen shakes hands with Oscar-nominated actor and Denver East High School graduate Don Cheadle before the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

AAron Ontiveroz, The Denver Post Wide receiver Emmanuel Sanders (10) of the Denver Broncos prepares to take the field during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



AAron Ontiveroz/, The Denver Post Quarterback Trevor Siemian (13) of the Denver Broncos prepares to take the field during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

AAron Ontiveroz, The Denver Post Quarterback Trevor Siemian (13) of the Denver Broncos prepares to take the field during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

Joe Amon, The Denver Post Cornerback Chris Harris (25) of the Denver Broncos waits for the Carolina Panthers to take the field for their first offensive possession during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



Joe Amon, The Denver Post Middle linebacker Luke Kuechly (59) of the Carolina Panthers forces a fumble on running back Devontae Booker (23) of the Denver Broncos on his first career carry during the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post Denver Broncos quarterback Trevor Siemian (13) runs off the field after their win over the Carolina Panthers 21-20 September 8, 2016 at Sports Authority Field at Mile High Stadium.

Helen H. Richardson, The Denver Post Bradley Roby (29) of the Denver Broncos tackles Greg Olsen (88) of the Carolina Panthers during the fourth quarter of the Broncos' 21-20 win. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



Helen H. Richardson, The Denver Post Greg Olsen (88) of the Carolina Panthers and Donald Hawkins (78) check the health of Cam Newton (1) after he was pummeled by Shaquil Barrett (48) of the Denver Broncos and Darian Stewart (26) during the fourth quarter of the Broncos' 21-20 win. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

Joe Amon, The Denver Post Quarterback Trevor Siemian (13) of the Denver Broncos hands off to C.J. Anderson (22) against the Carolina Panthers during the second quarter. The Broncos hosted the Panthers on Thursday, Sept. 8, 2016.

Joe Amon, The Denver Post Jonathan Stewart (28) of the Carolina Panthers is upended by Corey Nelson (52) of the Denver Broncos during the fourth quarter of the Broncos' 21-20 win. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



Joe Amon, The Denver Post Cam Newton (1) of the Carolina Panthers runs as Von Miller (58) of the Denver Broncos pursues during the fourth quarter of the Broncos' 21-20 win. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

Joe Amon, The Denver Post Kelvin Benjamin (13) of the Carolina Panthers is hit by Darian Stewart (26) of the Denver Broncos and, Aqib Talib (21) during the fourth quarter of the Broncos' 21-20 win. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post Middle linebacker Luke Kuechly (59) of the Carolina Panthers hits quarterback Trevor Siemian (13) of the Denver Broncos during the second quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



John Leyba, The Denver Post Outside linebacker Von Miller (58) of the Denver Broncos tackles quarterback Cam Newton (1) of the Carolina Panthers during the second quarter on Thursday, Sept. 8, 2016.

John Leyba, The Denver Post Quarterback Cam Newton (1) of the Carolina Panthers sits on the turf after being knocked down by middle linebacker Todd Davis (51) of the Denver Broncos during the second quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

John Leyba, The Denver Post Denver Broncos inside linebacker Brandon Marshall (54) gives a hug to Denver Broncos quarterback Trevor Siemian (13) after their win over the Carolina Panthers 21-20 September 8, 2016 at Sports Authority Field at Mile High Stadium.



(John Leyba, The Denver Post Denver Broncos outside linebacker Von Miller (58) comes off the field after their win over the Carolina Panthers 21-20 September 8, 2016 at Sports Authority Field at Mile High Stadium.

John Leyba, The Denver Post Graham Gano (9) of the Carolina Panthers misses a game-winning field goal against the Denver Broncos during the fourth quarter of the Broncos' 21-20 win. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post The Denver Broncos celebrate a missed game-winning field goal attempt by Graham Gano (9) of the Carolina Panthers in the fourth quarter of the Broncos' 21-20 win. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



John Leyba, The Denver Post Cornerback Bene' Benwikere (25) of the Carolina Panthers makes an interception as wide receiver Emmanuel Sanders (10) of the Denver Broncos looks on during the third quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post Linebacker Brandon Marshall (54) of the Denver Broncos takes a knee during the national anthem before the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

Joe Amon, The Denver Post Former Denver Broncos quarterback and Super Bowl Champion Peyton Manning hoists the Lombardi Trophy during a ceremony honoring the franchise's three Super Bowl titles before the start of the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



John Leyba, The Denver Post Peyton Manning hoists the Super Bowl 50 Lombardi Trophy during a ceremony honoring the Broncos' three Super Bowl titles before the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

John Leyba, The Denver Post The Bowlen family poses with retired Denver Broncos quarterback Peyton Manning before the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post Super Bowl XXXIII MVP John Elway hoists the 1999 Lombardi Trophy during a ceremony honoring the Broncos' three Super Bowl titles before the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.



John Leyba, The Denver Post Super Bowl XXXII MVP Terrell Davis hoists the 1998 Lombardi Trophy during a ceremony honoring the Broncos' three Super Bowl titles before the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, Sept. 8, 2016.

Joe Amon, The Denver Post Former Denver Broncos quarterbacks and Super Bowl Champions Peyton Manning (left) and John Elway stand on a podium during a ceremony honoring the franchise's three Super Bowl titles before the start of the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.

John Leyba, The Denver Post Retired Denver Broncos quarterback and Super Bowl champion Peyton Manning walks off the field after a Super Bowl trophy celebration before the first quarter. The Denver Broncos hosted the Carolina Panthers on Thursday, September 8, 2016.



But Broncos coach Gary Kubiak gave Siemian the starting job for one reason more than any other.

“We just have to continue to find our leaders on this team, and the guys that are going to step up when things get hard,” Kubiak said last month. Nearly every Broncos player asked about Siemian said the same thing: he’s calm and collected, even in rough waters.

So when Siemian crouched under center late in the third quarter, the Broncos trailing by 10, but seemingly with no shot, he coolly took over. He brought the Broncos back on two long drives in the fourth quarter, one of eight plays that ended on a 25-yard screen pass to Anderson and another of 10 plays that included a fourth-down conversion from Carolina’s 2-yard line and a 1-yard Anderson touchdown run.

“I trust the kid,” Kubiak said Thursday. “I was trying to get him in a rhythm. Let the kid know I have confidence in him. The only way you get better as a player is for your coach to trust you and put you in those situations.”

By the time Siemian jogged out from the sideline late in the game, with the Broncos clutching to a one-point lead, Denver fans stayed silent, trained in the ways of Manning demanding quiet play-calls. Siemian held on to the ball too long and took a 10-yard sack on third down.

“It’s definitely different when you’re on the field, but we played in a lot of big games last year,” Siemian said. “I tried to simulate that as much as I could. But, no doubt, it’s different when you get out there.”

But the Denver defense, as it did so often last season, held down a better offense in Carolina, stumping them on a game-deciding final possession. Newton led the Panthers into field-goal range, finishing with 194 yards on 18-of-33 passing. But Carolina kicker, Graham Gano, missed a 50-yarder with 9 seconds remaining.

The Broncos last season won 11 games by less than a touchdown. Siemian, like Manning before him, just needed to survive.