Peyton Manning of the Denver Broncos throws a pass in...

Peyton Manning of the Denver Broncos throws a pass in the first quarter against the Pittsburgh Steelers during the AFC Divisional Playoff Game at Sports Authority Field at Mile High on Jan. 17, 2016 in Denver. Credit: Getty Images / Doug Pensinger

Peyton Manning is nothing if not realistic.

As the 39-year-old quarterback squeezes every last drop out of the remaining days of his brilliant NFL career — his final game could be just days, or possibly weeks, away — Manning understands exactly why he now has a chance to play in another Super Bowl.

Just moments after the Broncos beat the Steelers, 23-16, to reach the AFC Championship Game, Manning was asked Sunday about the significance of his latest accomplishment. He smiled at CBS reporter Tracy Wolfson and said, “I think our defense is guiding us, let’s make that clear. I am honored to be a part of it and looking forward to playing next week in the AFC Championship Game.”

It will be Manning vs. Tom Brady for a 17th time in their illustrious careers, and almost certainly the last for the Broncos’ quarterback, who clearly is not the same player he once was and would be best served by walking away.

The storybook ending would be a trip to Super Bowl 50 in San Francisco against the winner of next Sunday’s Panthers-Cardinals NFC Championship Game, but there’s no guarantee Manning will get past Brady next week at Sports Authority Field at Mile High.

Manning’s arm is barely strong enough to run the Broncos’ offense, although he wasn’t helped by his receivers’ penchant for dropping passes against the Steelers. For the Broncos to have a chance against the Patriots, who looked sharp in Saturday’s 27-20 win over the Chiefs at Gillette Stadium, the offense will have to be significantly better.

After all, unlike the Steelers, who were without star receiver Antonio Brown and running backs Le’Veon Bell and DeAngelo Williams and got whatever they could out of Ben Roethlisberger — injured right shoulder and all — the Patriots’ offense is as healthy as it’s been all season.

Brady, meanwhile, is at the top of his game. Julian Edelman is back after a nearly two-month absence with a broken foot. And Rob Gronkowski, the premier tight end of his era, looks fine after battling through knee and back injuries in recent weeks. He had two touchdowns in the Patriots’ win over the Chiefs.

Despite Manning’s limitations, it still is terrific theatre and as must-watch a game as any in the 15-year history of their rivalry. Brady has an 11-5 advantage in the head-to-head matchup, but the quarterbacks are 2-2 in head-to-head playoff matchups, with Manning winning two of their three AFC Championship Game meetings.

Manning already is trying to downplay the individual rivalry. He even took a page out of Patriots coach Bill Belichick’s anti-hype manual.

“It will be the Broncos vs. the Patriots,” Manning said. “To quote Bill Belichick, ‘We’ll be on to New England.’ ”

Manning did show some flashes of his old form, enough to give the Broncos hope that he has one — and possibly two — more special moments before what almost certainly will be his retirement announcement.

His best pass of the game against Pittsburgh came when the Broncos needed it most. With the Broncos trailing 13-12 midway through the fourth quarter, on third-and-12 from the Denver 33, Manning threaded a perfect pass to wide receiver Bennie Fowler over the middle, and Fowler turned it into a 31-yard gain. The Broncos took the lead for good on the drive, and Manning was on his way to another game against Brady.

As always, Brady refused to shine a publicity-seeking light on himself or his opposing quarterback, no matter who it is. Same deal this time. Even before he knew he’d be facing Manning one more time, he was more concerned about his own team and his own performance.

“I think we had plenty of plays out there that we left on the field,” Brady said of the Kansas City game. “I think we need to be sharper next week, so that’s what we’re going to try to be. We’re going to need it.”

Brady hopes the result will be different from his last playoff game against Manning. The Patriots went quietly into the Mile High night as the Broncos beat New England, 26-16, in the AFC Championship Game after the 2013 season. Denver reached the Super Bowl, but Manning suffered one of his worst defeats: a 43-8 loss to the Seahawks at MetLife Stadium.

He hasn’t been the same since. Manning’s play declined badly in the second half of the 2014 season and he was completely ineffective early in 2015 before being sidelined by a foot injury and replaced by Brock Osweiler.

But it was Manning to the rescue after Osweiler struggled against the Chargers, and it was Manning who clinched the No. 1 seed in the AFC playoffs.

He thus earned the right to face Brady in the most optimal situation possible. Now he has to hope he again can hold off Father Time.