ENGLEWOOD, Colo. -- Undrafted rookie Chris Harris climbed the depth chart to start four games last season with a tenacious work ethic that was first noticed during offseason workouts.

That earned him some early-season playing time with the special teams unit – but as he continued to raise eyebrows on the Broncos' sideline, he found a niche during the second half of the season at nickel cornerback.

Now entering his second year in the league, the cornerback from Kansas knows that despite his success in 2011, his job isn't guaranteed in 2012.

"Being an undrafted free agent, you have to prove yourself every year," Harris said. "So I never stop working."

If he's going to maintain a similar role in a deeper, more talented Broncos' secondary, he'll have to show the same zeal that first caught the coaches' eyes last year – because experience isn't a factor the 22-year-old has in his favor.

This offseason, the team brought in three veteran defensive backs - cornerbacks Tracy Porter and Drayton Florence and safety Mike Adams. Combined, the three have played 21 years in the league.

But 2011 team captain Champ Bailey said he hasn't noticed Harris backing down from the competition.

"He's holding his own," Bailey said, noting that Harris always has a smile on his face. "That's one thing about him, he's such a competitor. He feels confident about what he does. He's just letting his play speak for itself." 

As for Harris, he believes the additions to the secondary can only help him.

"Its just something I can gain experience from," Harris said. "These guys have been in the league for a long time. They are just adding competition and just making me better.

"We all talked as defensive backs and said we're never going to give each other bad advice, always try to help each other," he continued. "The competition is only going to make everybody better."

Although the unit will work together to improve as a whole, no one has lost sight of the fact that most slots on the depth chart might remain blank through training camp.

"We all understand every spot is up for grabs, except Champ's," Harris said. "There's competition everywhere."

Surrounded by proven veterans, Harris' youth may count against him in the early goings. But to him, his young age only means more room for improvement and more time to learn.

"Really I just want to get faster and stronger," he said. "I'm only 22 years old. We drafted a guy that's older than me coming in, so I'm still young, still learning the game a lot more. There's a lot I can learn."

The draftee that Harris is referring to could be the 26-year old center from Baylor, Philip Blake. Or, it could be Omar Bolden, the 23-year old cornerback from Arizona State. Bolden is another name who will be fighting for those second, third, and fourth cornerback spots. Like Harris, Bolden was a four-year starter in college. But what Bolden hasn't done yet is go toe-to-toe with some of the NFL's top receivers. That kind of experience is what Harris hopes will make him a valuable asset to the Broncos' defense.

"Playing against top receivers like (Wes) Welker, Antonio Gates, I kind of got thrown in on the fly," Harris said. "Being able to go out there and play against those top guys definitely gives me confidence going into this season."

He earned playing time in Denver's two playoff games as well, making five tackles against Pittsburgh in the first round and starting against the Patriots in round two. 

"Not a lot of undrafted rookies get that experience in the playoffs," Harris said.

Regardless of the fact that nearly every defensive back -- young or old -- is trying to secure a spot on the depth chart, the true task at hand is the same for every member of the Denver Broncos.

"We're all here for one common goal, and that's to win a Super Bowl," Harris said.