ENGLEWOOD, Colo. — As Denver's offense took the field to open the fourth quarter on Sunday, it knew it had a chance to take advantage of a Pittsburgh miscue and put the Broncos in control.

The play before, Bradley Roby had popped the ball loose from Steelers running back James Conner, and Darian Stewart had recovered along the sideline. It was a major momentum swing. Tied at 17, Pittsburgh's offense had been driving down the field before the Denver defense forced the turnover, its third of the day.

But for that momentum to carry over to the fourth quarter, the Denver offense had to seize the opportunity ahead of it.

Enter Case Keenum, who had orchestrated a game-winning drive the week before.

After four consecutive runs to open the drive, the Broncos faced third-and-5 at their own 40 yard-line. At that point, the Broncos had been just two for eight on third downs, and they would need a big play from their quarterback to keep the drive alive.

Keenum took the shotgun snap, surveyed the field, stepped up to avoid pressure from Steelers All-Pro Cameron Heyward and found DaeSean Hamilton for 13 yards and a first down, showing patience and poise as the pocket collapsed around him.

Four plays later, the Broncos had moved into the red zone. Keenum threw a 14-yard dart down the middle to Emmanuel Sanders, who had enough time to get down and avoid taking a potentially big hit by the oncoming safety.

Two plays later, Phillip Lindsay was in the end zone and, following Brandon McManus' extra point, the Broncos led 24-17. It was a lead they wouldn't relinquish.

The drive that gave them that lead was the best of the day: 11 plays for 79 yards in 5:43.

Keenum accounted for 45 of those yards on four completions.

It's those types of drives — a mix of runs and timely, accurate short- and medium-depth passes — that are beginning to show Keenum's development and comfort in the Broncos' system. After throwing 10 interceptions in the Denver's first eight games, he hasn't turned the ball over once in the last three games.

"[I'm] just doing a better job of being smart with the ball," Keenum said Sunday. "[I'm] making better decisions. I think [Offensive Coordinator] Bill [Musgrave] and I are doing a great job of communicating. I think [Quarterbacks Coach Mike Sullivan] does a great job presenting the game plan and getting me ready to play. I think, that being said, we're … just getting comfortable with how [Musgrave]'s calling plays and what his mindset is and where he's attacking."

Keenum's ability to avoid turnovers doesn't mean he's not still looking for big plays, though. One such play, a perfectly-placed 38-yard connection with Sanders down the sideline in the third quarter, set up his touchdown toss to Sanders on the very next play.

"Case has played his best ball in the last three weeks taking care of the ball and still making plays" Joseph said Monday. "It's a fine line between that. Sometimes to make some plays, you're taking some chances, and he's been good with the ball and still making plays for us."

Of particular importance Sunday was the Broncos' red-zone performance, an area in which the team has been inconsistent. Denver found the end zone on three of its four trips Sunday, and Keenum was 5 of 6 for 34 yards and two scores inside the Steelers' 20-yard line.

"We find our playmakers down there," Joseph said. "Case has done a good job with the red zone and third-downs yesterday. That goes through the quarterback."

What makes Keenum's performance over the past few weeks even more impressive is that he's had to work through injuries at the positions around him, especially along the offensive line, where the Broncos' three interior linemen are playing new positions.

"That's his maturity," Joseph said. "He's a winner. I've never doubted Case, and he's playing better and better each week."

As the Broncos look to carry momentum into a potential playoff push, they will likely need Keenum to continue to be aggressive downfield but also recognize when an underneath throw is the better option. As he's shown over the past few weeks, that's a role he can fulfill as the season hits the stretch run.