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DENVER -- Ah, that growing list of Broncos playmakers: Peyton Manning. Von Miller. Demaryius Thomas.

Mitch Unrein?

Well, yes.

The second-year defensive lineman out of Wyoming played as big a role as Manning, Miller or anyone else Sunday in helping the Denver Broncos defeat the Tampa Bay Buccaneers 31-23 and wrap up their second straight AFC West title.

Unrein caught a 1-yard touchdown pass from Manning to open the scoring, then got the hit on Tampa Bay quarterback Josh Freeman that forced a bad throw. It ended up in Miller's hands, and, moments later, the end zone for the score that turned the game into a runaway.

"People are going to have to game-plan for that guy," cornerback Champ Bailey said.

Thomas caught two other touchdown passes from Manning, who now has 29 this year and passed Jake Plummer and John Elway for the most scoring throws in a single season.

The Broncos (9-3) won their seventh straight and wrapped up a date in January in the playoffs, though there were no champagne bottles being uncorked in the locker room.

"It's one step," Bailey said. "It's not like we've done everything we want to do."

The Bucs (6-6), surprising contenders under first-year coach Greg Schiano, fell a game behind Seattle for the second NFC wild-card spot and their loss clinched the NFC South for Atlanta.

They were in this game until Unrein made his second big play and set the stage for Miller's first NFL touchdown, which capped a 21-0 third quarter for Denver.

"The reality is, we get hit and throw the pick-6," Schiano said. "That changes the complexion of the game. Now we're not able to run the football. I mean, we didn't run it gang-busters in the first half. But we ran it. And ... if you're able to be in a game where you can run it, oftentimes you'll be able to run it in the fourth quarter."

The Broncos held Tampa Bay rookie Doug Martin to 56 yards on 18 carries.

Manning went 27 for 38 for 242 yards, as the Broncos scored 30-plus points for the sixth time over their seven-game win streak -- a night-and-day difference from last year, when they won the division at 8-8 and played close-to-the-vest, low-scoring games with Tim Tebow running the offense.

Yet despite Denver's big numbers Sunday, which included eight catches for 99 yards for Thomas and nine receptions for 89 yards from tight end Jacob Tamme, this was, yet again, a far-from-perfect effort from Manning and Co.

The quarterback was frustrated in this first half, as a series of penalties, off-target throws and missed protections kept him biding his time on the bench. The only real highlight came at the end of his first drive -- a 1-yard touchdown pass to Unrein, who became the first defensive lineman to catch a touchdown pass in Broncos history, then celebrated with a big-time spike.

"After I spiked it, I was, like, 'Uh, oh, where'd it go?' " Unrein said. "Luckily, I got it back."

Unrein's hit on Freeman in the third quarter also resulted in a touchdown -- this time, from Miller, who went 26 yards to make it 28-10. It was Miller's first career score and he celebrated by doing his dance thing, not in the backfield, but this time in the other team's end zone.

"When I got my hands on it, I felt like I only had some O-linemen in front of me," Miller said. "I felt like my odds were pretty good."

Before the Miller TD, this was a game.

Late in the first quarter, Freeman found Mike Williams in single coverage down the middle for a 40-yard gain. Martin followed with a 7-yard run, then another for 5, then Freeman found Manning's old buddy in Indianapolis, Dallas Clark, for an 11-yard touchdown and a 10-7 lead.

But when the teams came out after halftime, Denver was a different team.

"The hype these guys get, it's well deserved," Freeman said. "They get after it. The front four, they do a good job of timing their blitzes. The Denver defense played a great game today."

Manning wasn't bad, either. With his ninth completion, he surpassed Dan Marino for second on the all-time completions list. He now has 4,986.

On the second drive of the third quarter, Manning completed three passes on a quick, 52-yard touchdown drive for a 14-10 lead, capping it with an 8-yard pass to Thomas, who had a sliver of space in the back of the end zone.

After a three-and-out, Manning did it again, starting a 57-yard drive with a 14-yard pass to Tamme and capping it five plays later with a 10-yard score to Thomas, who beat double coverage.

"What I liked about the second touchdown was that Demaryius was seeing the same thing I was seeing," Manning said. "We had another route on. We changed it at the line. We were thinking along the same lines. I like to see the communication, the growth."

After the early touchdown drive, Freeman never got comfortable again.

He finished 18 for 39 for 242 yards. He led the Bucs on a 47-yard touchdown drive that made the score 31-23 with 2:33 left.

Denver recovered the onside kick and lined up in victory formation twice. Schiano, as is his wont, had his players challenge those plays, which led to some scrapping, but no coach-to-coach conflict the way Giants coach Tom Coughlin confronted Schiano under similar circumstances earlier this year.

"We were prepared for it," Broncos coach John Fox said.

Game notes

Broncos K Matt Prater missed from 47 yards, making him 2 for 5 from 40 to 49 yards this season and 15 for 17 from everywhere else, including 3 for 4 from 50-plus. ... Martin was held under 60 yards for the second straight week. ... Matthew Willis, getting playing time that would've gone to injured Brandon Stokley, had three catches for 22 yards.