DENVER – If Chad Kelly is not promoted by the Broncos' decision makers to No. 2 quarterback this week, then the competition is rigged.

Paxton Lynch has had his chances. But Kelly has been outplaying Lynch for a while now.

While Lynch struggled in the Broncos' 42-28 preseason-opening loss on a warm Saturday night at Broncos Stadium at Mile High, Kelly instantly developed a cult following from the crowd of 66,172 (more than 9,000 no-shows) that chanted, "Kelly! Kelly! Kelly!'' as he marched the team on two touchdown drives to cap his first two offensive series in the second half. He had a final drive end at the Vikings' 1-yard line as time expired.

"I'm excited for Chad, Chad's been playing really well,'' Lynch said. "He deserves that, he's a good kid and he's always supporting the people around him and working his tail off, too. I'm working the same way, and I'm trying to get better each and every day. The only way I can do that is focus on myself and get better day-in and day-out.

"But I'm proud of Chad. I'm glad that Chad had this opportunity and he got to play the way he did.''

The Broncos have two joint practices with the Chicago Bears at their UCHealth Training Center headquarters next week before playing them in preseason game No. 2 next Saturday at Broncos Stadium at Mile High.

Kelly did throw an interception deep in his own territory on his third series, a turnover that helped the Vikings convert with a clinching touchdown. No one is saying Kelly is a finished product after missing his entire rookie season last year to recover from surgically repaired injuries to his knee and wrist. But he brings an energy -- a 'Swag' which is what his teammates and coaches call him -- accurate passing from a push, baseball catcher-like delivery, and mobility that backup quarterbacks must possess. What are we missing? Isn't it time to give Kelly a promotion to No. 2?

"Well, we'll see,'' said Broncos head coach Vance Joseph. "We'll watch the tape and see where we are. Obviously, Case (Keenum) is our starter so that's my main concern. But Chad has played well. He played well tonight outside of the one interception, which led to a score for those guys. But he is a guy who plays with a lot of confidence.''

Kelly was 14 of 21 for 177 yards and a 104.7 passer rating. Lynch was ineffective, completing 6 of 11 passes for a mere 24 yards and an interception for a 22.2 rating.

"Obviously, I'm upset,'' Lynch said. "The interception early, kind of a freak play, batted in the air. And after that we just continued to start slow. Didn't really put a lot of drives together and move the ball so I'm upset we didn't score a lot of points, but I'll watch the film tomorrow and we'll move on from that and work on Chicago.''

Kelly threw touchdown passes of 36 yards to tight end Matt LaCosse and 19 yards to Phillip Lindsay. He's not concerning himself with whether he gets moved up to No. 2, and while that may be hard to believe, it is consistent with what he said last week, after he was the star of the Broncos' live scrimmage at their UCHealth Training Center headquarters.

"I can't look at that that way,'' he said. "I have to keep my nose in the playbook and keep studying. I should have studied even more on the man-zone reads, otherwise I wouldn't have thrown the pick. But it's not about that (moving up to No. 2). It's about we go out there each and every day, each and every practice, each and every snap. So game's over. We look forward to the Chicago Bears and get better tomorrow.''

If the Broncos don't believe Kelly is ready to be their No. 2 quarterback, don't be surprised if general manager John Elway starts looking outside the organization for an experienced quarterback who can back up starter Case Keenum.

If Bronco fans feel duped from reading, listening and watching all those glowing reports from training camp, repeat three times.

It’s only preseason. It’s only preseason. It’s only preseason.

Denver’s starters and second-stringers looked terrible in falling behind the Minnesota Vikings, 17-0 early in the second quarter of the preseason opener for both teams. The Broncos did move the score to 24-14 by halftime.

The Broncos' top first-half moments were an interception by linebacker Zaire Anderson that helped set up a 23-yard touchdown run by rookie running back Royce Freeman, and a 78-yard touchdown off a punt return by the once-beleaguered Isaiah McKenzie.

"It was huge for him,'' Joseph said. "He's obviously a talent. His issue last year (when he had five muffs or fumbles).It was more decision-making. We're helping him fix that so he can help us win games.''

Prior to the game, Broncos linebacker Brandon Marshall and receiver Demaryius Thomas did not come out to the field during the playing of the National Anthem – as was their right by the new NFL owners’ policy. The policy is currently stayed as the league and players union negotiate.

Still, Marshall and Thomas took their stance against what they perceive as social injustice without kneeling on the sidelines or sitting on the bench, as several NFL players did during the preseason-opening week.

"It's their right,'' Joseph said, adding he was unaware Marshall and Thomas would make their positions.

The Broncos were thoroughly outplayed early by a Vikings team that reached the NFC Championship Game last season.

The Vikings’ quarterback last season was Case Keenum. In their bid to take the next step to the Super Bowl, they let Keenum go and signed Kirk Cousins, a stronger-armed passer from Washington.

Minnesota’s decision-makers left smiling. In his one and only series, Cousins was 4 of 4 for 42 yards, including a beautiful 28-yard strike down the right sideline to Stefon Diggs that set up first-and-goal.

Cousins was aided earlier in the drive by back-to-back runs of 20- and 21-yard runs by Latavius Murray.

"I thought it was a great first drive,'' Cousins said. "It was a great start to the preseason.''

Keenum and the Broncos’ first-team offense had two series and went three-and-out in both.

"It's just frustrating not playing well and you don't have a chance to bounce back from it,'' Keenum said, adding he had no dispute with the coach's decision to pull him and the No. 1 offense after two series.

Keenum opened with a 5-yard completion to Thomas, but otherwise couldn’t get anything going against a Vikings’ defense that ranked No. 1 last year in both points and yards allowed.

"We obviously have some things to work on,'' he said. "I think it's a good test for us going against a really good team ... We know we've got to work, we've got to get better, hands down. I think all of the guys are hungry. Sitting there on the sideline, talking to those guys after we were out, every single one of them wanted more.''

Paxton Lynch came in with the Broncos’ second-team offense and on his second play and first pass, the threw high across the middle to tight end Austin Traylor. Although Traylor managed to get his hands on the ball, it ricocheted away for an interception.

Three plays later, Vikings backup quarterback Trevor Siemian – the Broncos’ starter the previous two years – picked up Denver’s blitz and threw a 13-yard touchdown pass to a wide-open Roc Thomas, the Vikings’ running back.

Siemian later threw a screen pass to Thomas, who raced 78 yards for a touchdown.

"It's a little weird for the first game back here,'' Siemian said. "Once you start playing you kind of forget about those things.''

The Broncos’ best player, outside linebacker Von Miller, was told about 20 minutes before kickoff to take his pads off.

"He's a guy who we can't lose, so we didn't play him, simple as that,'' Joseph said.

The Denver D was also hurt by the new laws against leading with the helmet. Starting safety Justin Thomas and backup safety Dymonte Thomas were each flagged for illegal contact penalties.

Siemian was 11 of 17 for 165 yards, two touchdowns and an interception by halftime. The Vikings had another former Broncos' quarterback who played well Saturday. Kyle Sloter was 9 of 11 for 69 yards with a touchdown, a 2-point conversion completion and a 14-yard touchdown run.

"It's not so much harsh feelings or ill-will,'' Sloter said. "It's just that I was excited to come back and see a bunch of friends.''

Bronco Bits

Lindsay was the Broncos' leading receiver as he had three catches for 40 yards and a touchdown out of the backfield. "I've got to polish my special teams,'' he said....

The most significant injury was to tight end Austin Traylor, who hurt is right shoulder.The Broncos should return two other tight ends, Jeff Heuerman (knee) and Troy Fumagalli (groin) next week. ...

Freeman (4 carries,38 yards) and Kelly (three carries, 38 yards) were the Broncos' leading rushers.