All rookies have been rookies before.

They just called them freshman back in college.

This is the mindset De’Angelo Henderson is taking as a rookie running back for the Denver Broncos. He is going back to the 2013 season at Coastal Carolina, where after a greyshirt year in 2011, and a redshirt year in 2012, Henderson as a redshirt freshman broke in with 599 yards rushing on a robust 7.3 yards per carry.

“Definitely, this goes back to my freshman year in college,’’ Henderson said after his 41-yard touchdown burst on the first play after the 2-minute warning lifted the Broncos to a 24-17 win against the Chicago Bears. “Even my freshman year in high school. You’ve got to prove yourself to the vets, show that you belong, show that you can compete. That you’re not afraid of the challenge.’’

The score tied, 17-17 with 1:58 remaining and facing a third-and-22, Broncos offensive coordinator Mike McCoy called a perfect play against the Bears’ extremely soft, prevent defense.

“It was a simple inside zone play,’’ Henderson said. “The defenders were playing off pretty deep and once I got the ball I knew I would have a chance to make something happen because they were playing off so far. Got it, hole opened up, burst through.’’

Left guard Michael Schofield opened the hole with a pancake block on a defensive tackle. Once Henderson got through the line, there was no Bear defender in the second level. He met safety DeAndre Houston-Carson at the third level, but sped past with a cut right.

It was the type of run where Henderson assuredly opened the eyes of the Broncos’ football decision makers.

“I’m hoping I did,’’ he said. “Got to take everything day by day and one game at a time but I’m hoping I did just to show I can compete. I’m a little bit smaller, a little bit shorter – I’m not small, short. But I can compete, it doesn’t matter my height. I can compete.’’

In fact, Henderson’s 5-foot-7 stature may have helped him on the run as he’s not easy to pick up until he’s at top speed.

Henderson finished with 54 yards on seven carries. A skeptic might note he only had 13 yards on six carries until his big run. An optimist would point out Henderson had three other carries for 25 combined yards that were called back by penalties.

From the team perspective, the only problem with preseason performances like the one Henderson had is they diminish the option of sliding him to the practice squad. The Broncos’ running back room is crowded with C.J. Anderson, Jamaal Charles, Devontae Booker, Stevan Ridley, Juwan Thompson and Henderson, plus fullback Andy Janovich. Bernard Pierce has missed virtually the entire training camp because of a hamstring strain.

The Broncos may only keep four from this group on their 53-man roster, possibly five.