Courtland Sutton smiled. P.J. Locke gasped.

Marvin Mims Jr. was given space on a crucial punt return in the fourth quarter against the Colts and all his teammates on the sideline knew something special was about to happen.

The second-year wide receiver — one of the best punt returners in the league — caught the ball on the far right side of Denver’s 25-yard line before sprinting to the left and down the sideline for a 61-yard return to Indianapolis’ 15.

Two plays later, quarterback Bo Nix threw a short pass over the middle to Nate Adkins that the second-year tight end turned into a 15-yard touchdown with a spin move and shake to give the Broncos a 17-13 lead with 13:51 to go.

It was the first blow landed in a 21-point fourth quarter Sunday at Empower Field at Mile Mile that gave the Broncos a 31-13 knockout victory and secured the team’s first winning season since 2016. And it all started with Mims in space.

“That’s why he’s the best returner in the entire NFL,” tight end Adam Trautman said.

The Broncos delivered an offensive performance to forget. Nix threw a career-high three interceptions, including two in the second quarter. They totaled just 72 rushing yards on 27 carries. And their third-down execution was a mess (6 for 17).

Denver needed someone to step up and ignite a spark. Mims turned out to be the guy.

The Oklahoma product averaged 32.3 yards on three punt returns. With 8:24 to go in the third quarter, Mims returned the ball 27 yards to the Colts’ 39-yard line. The Broncos, however, failed to capitalize, as Nix threw an interception to safety Nick Cross.

But when Mims gifted his team solid field position on his third return of the game, they took advantage.

“It’s like a gasp of air, like, ‘What is he going to do?’” Locke, Denver’s starting safety, said. “He’s dynamic. That’s all he needs is some space, man. I thought he was going to score twice, honestly. He keeps messing with us.”

For Mims, the key to being a successful punt returner is instinct. He said he has an idea of where to run the ball before stepping onto the field. However, there are moments when he has to change his direction in an instant.

Mims said the team’s ability to block down the field also contributed to his success.

“As punt returners, we are supposed to go left or right, but I never know where I’m going to go,” Mims said.

During the season as the Broncos have searched for ways to get Mims involved, the 2023 second-round pick has remained productive as a returner. He entered Sunday with 311 yards on 23 punt returns.

In the back half of the season, he has also made strides as a receiver. He has totaled 218 yards and two touchdowns on 12 catches in the last four games. But to beat the Colts and move the Broncos to within a win of their first playoff berth since Super Bowl 50, Denver needed Mims the returner. His 97 punt return yards against the Colts were a career-high.

“Him doing that, even if it’s 10 yards, is such a big momentum change for us,” Sutton said. “Watching him go down the sideline a couple of times today (was) exciting because at any moment you know that he could take it to the crib.”