Royce Freeman will replace Devontae Booker as the starting Broncos running back.

ENGLEWOOD – For a rookie, Royce Freeman sure was grown up about it.

He was told Monday morning before the start of practice that he was now the Broncos' No. 1 running back, which means starting in the season opener Sunday against the Seattle Seahawks. Asked repeatedly, in various ways, what it meant to him and how it felt, Freeman spoke in a low monotone accompanied by flatline-like emotion.

"It's an honor,'' he said, finally flashing a humble smile. "Just like anything to be named a starter for this football team definitely is something that means a lot to me but I feel like I have to go out there and work hard.''

Freeman will be the Broncos' first rookie running back to start week 1 since Terrell Davis in 1995. Davis had a sensational four-year run that led to two Super Bowl titles and eventual induction into Pro Football Hall of Fame.

“It’s an honor to be mentioned with men of that caliber, with players with that type of legacy around here,'' Freeman said. "It makes you want to work harder and honestly, take it day by day and not get too far ahead of yourself.’’

Freeman replaces Devontae Booker, the third-year back who had been the starter through the first three preseason games. Which was news to Booker.

"I haven't really heard anything about it,'' Booker said. "I don't know. I'm supportive either way, I'll just go out there and do my job and continue to be me.''

Freeman was a four-year starter for the Oregon Ducks, who averaged 1,405 yards and 15 touchdowns a season. The Broncos took him with their No. 71 overall draft pick in the third round, a slot that gave him a $997,020 signing bonus and $480,000 first-year salary.

In the preseason, Freeman rushed for 84 yards and three touchdowns on 15 carries for a 5.6-yard average. Booker rushed for 33 yards on 9 carries for a 3.7-yard average. His two-year career average is 3.6 yards per carry.

Broncos head coach Vance Joseph said he would use all three backs – Freeman, Booker in passing downs and undrafted rookie Phillip Lindsay – against a Seattle defense that ranked 19th against the run last year with 114 yards a game.

But for the estimated 59.3 million people who played in a fantasy football league last year, Freeman is your guy. Don't worry about his youth. In fact, embrace it. The league's leading rushing rusher last year was Kansas City rookie Kareem Hunt. The league's rushing title in 2016 went to Dallas rookie Ezekiel Elliott.Rams rookie Todd Gurley II was the third-leading rusher in 2015.

The Broncos had no qualms about giving Freeman starter responsibility.