CHARLOTTE, N.C. -- Undrafted rookie Bryan Cox is yet another example of how long Carolina Panthers defensive end Julius Peppers has been in the NFL.

Cox's dad and Peppers played in the league together.

Cox Jr. is the son of three-time Pro Bowl linebacker Bryan Cox, who won a Super Bowl with the New England Patriots in 2001 and almost won another as the defensive line coach of the Atlanta Falcons last season.

That the younger Cox has spent his first preseason learning from the 37-year-old Peppers is a bit ironic because his dad was in the league with New Orleans when the nine-time Pro Bowl selection began his career at Carolina in 2002.

"It's crazy," said the 23-year-old Cox Jr. "Sixteen years, that's a long time playing ball."

Even the elder Cox, who spent 12 years in the league, agrees with that.

“That’s a credit to him keeping himself in shape mentally and physically,'' he said of Peppers. "That part of the game doesn’t get talked about enough. But when you take care of yourself and your body, that’s a credit to him being able to play well for a long time.’’

Cox Jr. joins first-round pick Christian McCaffrey as a Carolina player whose father played in the NFL.

The difference is McCaffrey is a lock to make the roster. Cox Jr. isn't.

That makes Thursday's preseason finale against Pittsburgh critical for the former University of Florida star. He must make an impression at a position that already is loaded with future Hall of Famer Peppers plus Charles Johnson, Mario Addison, Wes Horton and third-round pick Daeshon Hall.

That Cox Jr. wasn't intimated by that when he signed with Carolina over other teams speaks volumes to the confidence he has in his ability.

"It says he likes a challenge," coach Ron Rivera said. "The young man has got some ability. He's still got some growing to do, but he most certainly has caught our eye and most certainly has shown his improvement every week."

After getting passed over in the draft, Cox Jr. chose the Panthers over Tampa Bay on the recommendation of his father -- he calls him Pop -- who considers Carolina's Eric Washington the best defensive line coach in the league. Even if he hadn't been fired by Atlanta after the run to the Super Bowl Cox wouldn't have been interested in coaching his son.

“I wanted him to get out of my shadow,'' he said. "I’ve had my career and done my thing. Now I want him to do his.’’

But most importantly, Cox wanted his son to play for Washington.

"He thinks I can improve under him," Cox Jr. said.

Washington already has helped.

"Oh, man. I've learned a lot," Cox Jr. continued. "He's tightened up my technique, got me coming off the ball and playing my keys. ... It's a great system. We're a penetrating front. We get off the ball and we get vertical and disrupt."

Cox has noticed his son's improvement, particularly getting off the ball on the pass rush, which wasn't his forte in college.

“He was good against the run at Florida,'' the elder Cox said. "If he can improve in his pass rush abilities he’ll be set to have a nice long career somewhere.’’

Cox Jr. helped his cause in last Thursday's preseason win at Jacksonville. Given a chance to rotate in with the first-team defense, he got a sack in the second quarter.

"He's obviously got some good background and some good roots, and he's shown very well," said Rivera, who was an assistant linebackers coach at Chicago during part of Cox's career with the Chicago Bears in the mid-90s.

Good roots, but Cox Jr. didn't inherit all of his father's qualities. Cox was a bit of a renegade during his career. He totaled fines of close to $150,000 for everything from fighting to accusing the NFL of racism to spitting toward fans in Buffalo as he walked off the field.

And oh, in 1996 while playing for the Bears, Cox was fined $87,500 for making an obscene gesture at an official followed by some cursing.

Cox Jr. is much more laid back.

“He can get hot under the collar, but he does a better job than I did at not letting it fester and boil,'' Cox said. "Usually he kind of gets it out of his system so he doesn’t get that big explosion. But he does get hot under the collar as well. He is a competitor. He’s not afraid to let his feelings be known. He’s been raised to be a man. He’s no boy.’’

Cox did his best not to interfere with his son's coaching. But Cox Jr. did learn a lot following his dad around the league.

"Everything I'm seeing now, I've already seen it," he said. "So it's not really like a shock or anything like that because I've been around the NFL a long time. Now being in it myself, it's a little bit different.

"I was an outside looking in. Now I'm inside. You've just got to keep grinding."

Cox Jr. has to grind. He went from being a projected third-rounder following his junior season in which he had career highs in tackles (45), tackles for loss (10.5) and sacks (3.5) to undrafted following an injury-plagued senior season.

"Man, it was tough," Cox Jr. said of having to spend the three-day selection process without hearing his name called. "Injuries just piled up and it didn't end well for me."

Cox Jr. moved on. Now he's focused on making an impression as he approaches the preseason finale.

His dad has helped with simple advice.

"Just keep your head down and keep working," Cox Jr. said. "That's all, really. Just take it day by day and grind."

Studying Peppers, the second pick of the 2002 draft, also has helped.

"Well Pep, he's just a real, even-keeled chill kind of guy," Cox Jr. said. "Just learning his approach every day, just one day at a time, one play at a time, one drill at a time, just compartmentalizing different periods of practice and taking it period by period."

Because Peppers and Johnson are in the final year or years of their career also factored in the decision for Cox Jr. to sign with Carolina.

"My feeling was although Carolina was really deep at the position they had a couple of guys that were older and maybe moving,'' the elder Cox said. "But the big reason for me was Eric Washington. Having been in the division, having watched his guys play, I felt like he was the best coach in the NFL on the defensive line.''

Regardless of what happens on Saturday when rosters are cut to 53 players, Cox Jr. likes what he has put on tape for the Panthers or any other team that might be interested in him.

"I've given it everything I have," he said. "It's either going to be good enough for this ball club or hopefully another one. But I've done everything I can do."

That approach also is something he got from his dad.

“The thing I try to impress on him is don’t worry about whose there and the numbers,'' Cox said. "You just do what you’re capable of doing. If you do that you’ll be somewhere.’’