An incredible run by the Broncos got underway when it was indeed sunny in Philadelphia on an 80-degree day Sunday, Oct. 5.

The Broncos had started the season 1-2, losing in Weeks 2 and 3 on game-ending field goals at Indianapolis and at the Los Angeles Chargers. They then evened their record with a 28-3 home rout of outmanned Cincinnati, which had recently lost quarterback Joe Burrow for what would be two months with a toe injury.

On that sunny day in Philadelphia in Week 5, things looked dark for the Broncos when they trailed 17-3 early in the fourth quarter. But they stormed back to win 21-17.

That was the second of what now is a nine-game winning streak. Seven of the wins during the run have come by four points or less, the latest a wild 27-26 overtime victory at Washington on Sunday night.

“It starts with the belief and confidence, and that has to be earned,’’ coach Sean Payton said Monday of all the close games his Broncos have pulled out to raise their record to 10-2. “You go back to Philly. We were in some close games last year and our numbers weren’t as good. So, at some point you have to demonstrate it, do it, and there’s a belief you can do it and then there’s that confidence you’re going to do it. But it starts with the execution and then it has to happen.”

It has happened plenty lately. After the upset of the defending champion Eagles, the Broncos won 13-11 over the New York Jets in London in Week 6 on a late Wil Lutz field goal. They scored 33 points in the fourth quarter to stun the New York Giants 33-32 in Week 7 on a Lutz last-play field goal.

After a rare 44-24 breather against Dallas in Week 8, they won 18-15 at Houston in Week 9 on another last-play Lutz field goal. Then it was an ugly 10-7 win over Las Vegas in Week 10. Then Lutz won his third game this season on a last-play field goal, 22-19 over Kansas City in Week 11.

After a bye week, nothing changed with Denver drama. The Broncos defeated the Commanders when outside linebacker Nik Bonitto batted down a two-point conversion pass from Marcus Mariota on the final play.

That followed RJ Harvey scoring on a 5-yard run with 6:59 left in overtime for a 27-20 Broncos lead and Mariota throwing a 3-yard touchdown pass to Terry McLaurin with 2:47 left to pull Washington within a point.

“It is truly, I believe, like a culture belief,’’ tight end Adam Trautman said Monday about Denver’s run of winning close games. “Everybody wants to play for each other in the locker room and there’s just this feeling that you can’t really describe that you never really truly feel like you’re out of it. I know that we feel that way specifically on offense because of how great our defense is, so I would say that’s why we’re able to pull a lot of these games out and then learning from earlier games in the year.”

As Payton mentioned, the Broncos had issues in close games last season. They went 1-6 in one-score games, which included gut-wrenching losses of 16-14 at Kansas City, when Lutz’s last-play 35-yard field goal was blocked, and 30-24 in overtime at Cincinnati. Then things were repeating themselves this season in losses of 29-28 to the Colts and 23-20 to the Chargers.

But everything has changed since then.

“I would say in the four years I’ve been here, I don’t know if we’ve lived this way,’’ linebacker Alex Singleton said in Landover, Md., after Sunday’s game. “I think this locker room believes in each other so much and I don’t know we’ve had that in the four years I’ve been here. I think this year is different. This team is different.

“At this point, let’s just play every game a one-score game. It seems like we’ll find a way to do it. That’s what you want with this locker room. Every time, it’s been different (in winning close games). It’s been special teams, it’s been offense, it’s been defense. … Playing a complete game would be nice for four quarters, but that’s not how this league works. So to just continue to find ways to win is important.”

On Sunday, the offense and defense both stepped up when needed. In overtime, Bo Nix led the Broncos on a five-play 76-yard drive to Harvey’s touchdown, the big play a 41-yard Nix pass to tight end Evan Engram. Then Bonitto, who leads the vaunted Broncos defense with 10.5 sacks, made a play bigger than any sack he has had all season.

“I was told a long time ago by one of my many offensive coaches that pressure is a privilege, and not many people get to be in that opportunity,’’ Nix said after completing 29 of 45 passes for 321 yards and a touchdown against the Commanders. “So, if it’s going to be me who gets this opportunity, I am going to make the best of it. It doesn’t always go your way. Fortunately for us, it’s gone our way in these games. Last year, we were on the opposite end of these close ones.”

After the win at Philadelphia, Nix mentioned all the previous close losses the Broncos had and said “today went our way.”

It’s still going Denver’s way.