DENVER » No, you’re not seeing things.

That really was Peyton Manning lumbering his way down the field for a 12-yard gain and a first down Sunday. And thanks to his defense, that will be Manning — the 39-year-old quarterback who was supposed to be on his way to a retirement party — and the Denver Broncos, not Tom Brady and the champion New England Patriots, playing in the Super Bowl two weeks from now.

Ol’ No. 18 engineered Denver’s 20-18 victory — not settled until Broncos cornerback Bradley Roby picked off Brady’s pass on a 2-point attempt that would have tied it with 12 seconds left.

Brady hit a double-covered Rob Gronkowski in the back of the end zone on fourth down to set up the potential tie. The Patriots had to go for 2 because Stephen Gostkowski missed an first extra point in the first quarter, his first miss in 524 tries.

Aqib Talib stepped in front of Brady’s pass and deflected it skyward.

Roby, who forced the game-changing fumble in last week’s victory over Pittsburgh, made the pick. The Broncos (14-4) recovered the onside kick and the celebration began. Manning is now 6-11 in his vaunted series against Brady, but 3-1 with the AFC title on the line.

“He’s going to do what he has to do to win,” Broncos coach Gary Kubiak said. “He’s one of the greatest competitors ever in this league.”

Manning surpassed his boss, John Elway, as the oldest quarterback to take his team to the Super Bowl. The Broncos will play Arizona or Carolina, who met later in the NFC title game.

New England (13-5) came up short and won’t get a chance to defend its title. The Patriots lost their last two regular season games to squander home-field advantage. In a game that came down to one play, that may have made a difference.

“A couple of plays here and there, where they made better plays, really were the deciding factors of the game,” Patriots safety Devin McCourty said.

Whether it’s been Manning lining up under center this season, or Brock Osweiler, who took snaps while Manning was injured for six weeks toward the end of the season, the Broncos have depended on a defense that gave up the fewest yards and came up with game-saving plays time and again.

Von Miller finished with 2 1/2 sacks and an interception. The Broncos harassed Brady all day. He finished 27 for 56 for 310 yards and two picks. After giving it up twice on downs inside the Denver 20 late in the fourth quarter, Brady lobbed a 40-yard pass to a double-covered Gronkowski to keep a desperation drive going on fourth-and-10.

Then, on fourth-and-goal from the 4 with 12 seconds left, Brady found Gronkowski again. The tight end stepped in front of Chris Harris Jr. for the catch, and the game came down to one play.

The Broncos defense made it once again, and the franchise is now headed to its eighth Super Bowl. This marks No. 4 for Manning, who could become the first quarterback to lead two different franchises to titles. His last appearance was ugly. A 43-8 loss to Seattle two years ago.

Was this Vintage Manning against the Patriots? Not by a longshot.

For one, “Vintage Manning” has never been known for taking off when the field is clear, the way he did with 9:49 left in the third quarter and nothing but air between him and the first-down marker on the Patriots sideline.

“For him to take off and make that play, I can’t tell you how he’s led the team the last three weeks,” Kubiak said.

The 17-for-32 performance wasn’t one of his best, and Owen Daniels won’t be on Manning’s list of all-time favorite targets. But 17 completions was enough, and it was Daniels, the tight end who has played his whole career with Kubiak, who caught both of Manning’s touchdown passes.

Faced with the new title of “Game Manager,” Manning made the best playoff scramble by a Broncos quarterback since Elway helicoptered his way to a first down in the Super Bowl 18 years back to help the Broncos finally break through.

More fresh in the minds of Broncos fans was Manning’s decision to pull up and throw in the playoff game against the Colts last season when he had as much or more open space in front of him as he did Sunday. Some thought his career might be over after that one.

Nope. Not after this one, either. There’s at least one more game in his future — Feb. 7 in Santa Clara, California.