NASHVILLE, Tenn. -- Harry Douglas is standing on the sidelines of a Tennessee Titans practice tightly gripping a play sheet in his hand. He's bouncing between young receivers who show the slightest hint of uncertainty in their assignment or technique. He hands a bottle of Gatorade to a couple of wideouts during their humid outdoor session then he jogs back to clean up the wide receivers arches following the completion of that drill.

Occasionally, Titans offensive coordinator Terry Robiskie or receiver coach Frisman Jackson glance his way and smile. They were in his place once. But it's Douglas who has hopes to be in their shoes one day.

Douglas, on injured reserve with a knee injury, has been called "invaluable" by head coach Mike Mularkey and "leader of our room" by second-year receiver Tajae Sharpe. Now, he's moonlighting as a Titans player-coach. He's on the field during every practice, travels to road games, and has an earpiece in to listen to the calls during games. It's a glimpse into what he hopes will be a second career.

Harry Douglas, who is on injured reserve, is now moonlighting as a Titans player-coach. Rich Graessle/Icon Sportswire

"Yeah, I want to coach, when I'm done playing," Douglas, 33, said. "I just love the game of football. I love the excitement it brings. I love the brotherhood it brings. We're the best sport in the world in my eyes. I love everything that football has to offer -- we all chasing that ring."

The future of the Titans receiver core is young, with Rishard Matthews being the only contributing wideout over 22 years old who is under contract after this season. The development of first-round pick Corey Davis, third-round pick Taywan Taylor and Sharpe will go a long way in determining how explosive the Titans offense can be now and in the long-term. Douglas wants to make sure they all shine.

"He's been a huge help to me," Taylor said. "He definitely has played a role in the development of my game. He understands all the defenses, coverages, cornerback techniques and tendencies. I definitely try to pick Harry's brain."

Douglas brings a unique energy with unfiltered jokes, motivating trash talk and detailed instruction on route-running from a player's perspective. He can quickly switch from pumping up practice squad receiver Darius Jennings for beating Adoree' Jackson on an out route in practice to teaching recently promoted receiver Zach Pascal the correct hand position to catch a specific pass.

One day late in training camp, Douglas instructed quarterback Marcus Mariota to get some post-practice reps on corner routes with Taylor. He saw some improvements needed to get that fluidity where it needed to be. Mariota quickly said yes and spent several minutes with Taylor after practice working on it.

"I want to help make the game as easy as possible for them," said Douglas, who trails tight end Delanie Walker by one month as the Titans' oldest player. "They can call me anytime. They can ask me anything. Those are my little brothers. I want those guys to be successful more than anybody."

"He's very smart. He's got a personality to deal with players ... As far as teaching the position, the routes, the techniques, all the skills that go with it, Harry could do that easily." Mike Mularkey on Harry Douglas

Douglas said this element of his game -- willingly and voluntarily coaching players who could take his job -- evolved after his third NFL season. It wasn't intentional, he says, it's just who he is. Because of that, coaching became a desirable life progression.

There doesn't appear to be much question about whether he could do it. His first preference is coaching NFL, with college football second.

"He's very smart. He's got a personality to deal with players, especially at a position that has a lot of personalities," Mularkey said. "As far as teaching the position, the routes, the techniques, all the skills that go with it, Harry could do that easily."

Douglas believes he still has "some years left" playing in the NFL and there's a chance he could be designated to return off IR and help the Titans on the field by midseason. He said he felt like he was in the best shape of his life before he felt pain in his knee toward the end of training camp.

Whether next season or in 2022, Douglas appears to have found his second career at a time where many guys struggle to find a new life outside of playing football.

Douglas has had casual conversations, mostly with Jackson, but also with Robiskie, Mularkey and one of his former receiver coaches, Shawn Jefferson, about their transitions from NFL player to coach.

Injured Titans receiver Harry Douglas watches the other receivers during a recent practice. Cameron Wolfe/ESPN

Mike Vrabel (Texans defensive coordinator), Byron Leftwich (Cardinals quarterbacks coach), Jerricho Cotchery (Panthers assistant receiver coach) are a few players who have made a relatively smooth transition from player to coach this decade.

Mularkey said the transition was easy for him because he knew the nuances of the game, but he couldn't physically play anymore. Coaching became a natural shift. He figures Douglas would have success while noting game planning would be something he'd have to get comfortable with.

Robiskie agrees, but he says the hardest element for a player transitioning to coaching is job security. Douglas, who has a wife and a young daughter, would have to weigh if he could do that.

"It's a whole new life. No matter success or failure -- our rule is every three or four years you gotta move," said Robiskie, who has coached for six NFL teams. "That's OK when you're a young football player. I know some coaches who have been on 11 football teams."

Douglas, now entering his 10th NFL season, has played for just two teams, the Falcons and Titans. He'll likely have deeper conversations with his family when it's time to make that decision, but he points to his passion toward the game and NFL brotherhood as a reason why he'll try to stay attached to it.

"Harry's one of them guys that you'll have to drag off the field and tell him you can't play anymore," Robiskie said. "He just wants to be around. He's definitely capable of doing it at the coaching level."