DENVER -- Patrick Mahomes II made his first NFL start and his first NFL relief appearance a success.
After handing off a two-touchdown lead midway through the fourth quarter in his spectacular NFL debut, the rookie first-round quarterback returned to rescue the Kansas City Chiefs , driving them 67 yards in 11 plays to beat the Broncos 27-24 on Harrison Butker's 30-yard field goal as time expired at Sports Authority Field at Mile High.
"You always have to be ready," Mahomes said. "All season long, it's kind of been the same thing -- you have to make sure you're ready to go at any moment."
The Chiefs (10-6) will go back to starting Alex Smith for their wild-card game Saturday against Tennessee, even more secure in the knowledge they have a clutch backup in Mahomes, the former Texas Tech standout they selected with the 10th overall pick in April.
"He played fantastic," said Kareem Hunt, who secured the league's rushing title by scurrying 35 yards for a touchdown on his only carry.
Smith and several other starters rested because Kansas City was locked into the No. 4 seed in the AFC playoffs, allowing coach Andy Reid to essentially use this regular season finale as a playoff bye.
"It was good to get a couple bumps and bruises healed up," Reid said.
Von Miller said he was impressed by Mahomes, whom he expects to see plenty of in the coming years.
"He's great," Miller said. "He's the quarterback of the future for the Chiefs."
The Broncos (5-11) head into another offseason still searching for their quarterback of the future -- and maybe their fourth coach in five years after Vance Joseph oversaw a team that lost eight times by double digits and oversaw an eight-game skid, their longest in 50 years.
Joseph, who inherited what was seemingly the best situation of the half dozen new coaches in 2017 only to finish with the worst record of the bunch, will meet with general manager John Elway on Monday to discuss his future.
"I want to be here," Joseph said. "It's a football team that's close. We have to make some adjustments in some places, but our football team all year has not stopped working. That was fun to see, even tonight. It's been a hard year but everyone kept fighting. I want to be here to fix it."
Mahomes became the first quarterback drafted by the Chiefs to win a game for them since Todd Blackledge in 1987. He threw for 284 yards on 24-of-35 passing with no touchdowns and an interception.
Mahomes thought his day was won at 24-10 and Reid sent in Tyler Bray, who handed off late to fullback Anthony Sherman, who carried 14 times for 40 yards after coming into the game with six career carries in seven NFL seasons.
Linebacker Zaire Anderson scooped up the loose ball and scored from 38 yards out to pull the Broncos to 24-17.
After the Chiefs punted, Lynch added a 6-yard touchdown pass to Demaryius Thomas on fourth down with 2:53 left, and Brandon McManus' extra point tied it, 24-24.
Mahomes took off his jacket, put on his helmet and returned to the game with 2:45 left. He was sacked by DeMarcus Walker but recovered nicely to drive Kansas City to victory.
C.J. Anderson gained 61 yards to top 1,000 for the first time in his five years with the Broncos.
"It was tough," said Anderson, who carried 18 times.
Broncos quarterback Paxton Lynch was 21 of 31 for 254 yards with two touchdowns, two interceptions and was sacked five times.
He threw an interception late in the first half and was sacked three times in a five-snap span in the third quarter, losing the ball on one of them with linebacker Ramik Wilson scooping it up and scoring from 11 yards out.
It was 17 degrees at kickoff, the fifth-coldest home start in Broncos history and the coldest temperature for any of Lynch's starts, in the pros or at Memphis.