With the Vance Joseph Watch on loud timer, the Denver Broncos' junior varsity took on the Kansas City Chiefs JV here Sunday on a cold, overcast Sunday afternoon in the regular-season finale.

For Paxton Lynch and De'Angelo Henderson, you've got to start somewhere.

On the last day of a terrible Broncos' year, Denver rallied from two touchdowns down to tie up the Chiefs. But then Chiefs' quarterback Patrick Mahomes II was reinserted into the game and made a couple of outstanding plays in directing a final-drive field goal for a 27-24 win.

Mahomes looked like the real deal.

"I wouldn't call him the real deal but he has an arm, though,'' said Broncos linebacker Brandon Marshall. "He has a cannon. He's running this way and he throws across his body and the guy catches it. I think he has all the talent. He has all the tools. But I'm not going to call him the real deal, yet.''

The temperature at kickoff was 17 degrees, which was tied for the fifth coldest home game in Broncos' history.

As has been reported all week by 9NEWS, Broncos general manager John Elway is to decide on whether to retain Joseph, the Broncos' first-year head coach with a four-year contract, for a second year.

It had been reported Sunday morning by ESPN that Joseph was now "facing long odds to return." Elway and Joseph did not talk about the coach's future, or the report prior to the game.

"I saw the report,'' Joseph said. "Our coaches saw the report, but what are you going to do there? There was a game to play.''

A source close to Elway told 9News the Broncos' general manager had not yet made his decision, was going to sleep on it before making his decision Monday morning. Elway and Joseph will meet Monday morning. There is a chance Joseph will be retained.

The Broncos were down, 24-10 in the fourth quarter when Chiefs coach Andy Reid pulled Mahomes with 7 minutes left in the game. Mahomes was making an impressive NFL debut in place of starter Alex Smith, who was one of several Chiefs' starters who didn't play because the game lacked playoff implications.

But Chiefs' No. 3 quarterback Tyler Bray fumbled the handoff exchange on his first play and Broncos' linebacker Zaire Anderson returned it 38 yards for a touchdown. Then after a three-and-out by the Denver D, Lynch snapped his mid-game slump by directing a game-tying touchdown drive he capped with a fourth-and-4, 6-yard scoring toss to Demaryius Thomas with 2:58 remaining.

"I'm very proud of myself and this group on how we continue to battle against adversity tonight,'' Lynch said.

The Broncos' first-round quarterback in last year's draft, Lynch flashed signs of busting out in the final game of his second season as he began 13 of 16 for 159 yards, including a 29-yard touchdown screen pass to Henderson, a sixth-round rookie running back.

But Lynch couldn't sustain his play in what was the fourth start of his career. In the final seconds of the half, with the Broncos already in field goal range, Lynch forced a pass into traffic across the middle and was intercepted. Late in the third quarter, Lynch fumbled while sacked by Chris Jones. Ramik Wilson picked it up and returned it 11 yards for a touchdown.

And then in the fourth quarter, after moving the Broncos to the Chiefs' 11, Lynch took a sack, then on fourth-and-15 from the 16 threw a what-do-you-have-to-lose interception near the goal line.

At that point, there might have been 25,000 still in the stands watching the Broncos disappointing season wind down. At 5-11, the Broncos will get the No. 5 pick in the 2018 NFL Draft.

The Chiefs rested several key starters as they already had clinched the AFC West Division the Broncos used to own. Unable to move up, and without fear of moving down, from the No. 4 playoff seed, the Chiefs rested starting quarterback Alex Smith, tight end Travis Kelce, pass rusher Justin Houston, receiver/returner Tyreek Hill, cornerback Marcus Peterson and linebacker Derrick Johnson among others.

The Broncos played starting cornerbacks Aqib Talib and Chris Harris Jr. and safety Darian Stewart for a quarter, then turned the rest of the game over to three rookies: Brendan Langley, Marcus Rios and Dymonte Thomas. The team also spelled Von Miller, Brandon Marshall and Domata Peko more than usual.

Mahomes was 22 of 35 for 284 yards. He was intercepted by Stewart in the first quarter. Lynch finished 21 of 31 for 254 yards, 2 touchdowns and 2 interceptions.

"I felt like I played well but at the end of the day ... it's not an individual sport,'' Lynch said. "It's a team sport so overall we didn't do enough to win the game. We could have played better.''

The Chiefs scored easily on their first possession with star running back Kareem Hunt rushing 35 yards for a touchdown. Hunt then joined the other Chiefs' standouts on the sidelines for the rest of the game.

Henderson, who looked good in the preseason but wasn't active for 11 consecutive games this season, turned a short screen from Lynch and broke two quick tackles before speeding into the end zone for the Broncos' only touchdown in the second quarter.

"I tried to show a little something,'' Henderson said. "When I get in I try to take advantage of my opportunity whether it's one play or 50. As long as I'm in there I'm going to showcase what I got.''

Broncos' running back C.J. Anderson entered the game needing 54 yards for his first 1,000-yard rushing season. Kansas City seemed to know of the Broncos' offensive intentions as it took Anderson 18 carries to rush for 61 yards and he was taken out early in the fourth quarter after reaching 1,007 yards.

"It was the hardest ever,'' Anderson of the work he needed to reach his goal. "I kept pushing, kept grinding. They were doing everything they could to keep me away from it but we got it.''

Broncos receiver Demaryius Thomas needed 108 yards for his sixth consecutive, 1,000-yard season. He fell short with six catches for 57 yards. He wasn't the only Bronco to fall short this year.