CHARLOTTE, N.C. — Chargers coach Jim Harbaugh returns Sunday to where it all ended for him, and also where it began.

He was a 38-year-old quarterback, hoping for a few more years in the NFL, when he joined the Carolina Panthers for the 2001 season. He didn’t believe his career was at an end. After all, he was throwing passes to standout rookie Steve Smith, but the football gods had other ideas, as he recalled.

Although he never played in a game for the Panthers, the franchise left an indelible mark on Harbaugh and, in the end, it led him to a different career path. It was then and there that he began to realize he could turn to coaching, following in the shoes of his successful father, Jack.

So, Harbaugh began hanging out in the film room long after practice ended and his teammates headed for home. He sat on the floor and watched and listened as the coaches broke down film and discussed schemes and ways in which they could exploit their opponents while covering for their own shortcomings.

Harbaugh also met Greg Roman, a Panthers assistant coach who would join him at a number of stops over the years, including this season with the Chargers. Earlier this week, Roman remembered Harbaugh as an attentive student, a man who might become an excellent coach one day.

“I met Greg in Carolina, yeah, that’s as profound as anything,” Harbaugh said recently. “Nothing more profound than meeting Greg Roman in Carolina. He was an offensive line assistant. I was at the point where I was coming in new. I was in the office late, just watching the coaches.”

Said Roman, recalling his first impressions of Harbaugh: “He was always in the film room, always. He’d be sitting in our special teams coach’s office on the floor watching film with the special teams coach at night. What does that tell you? A quarterback doing that? He was grooming himself to become a coach.”

It wouldn’t be long before Harbaugh turned in his helmet and pads.

“I didn’t get into a game, it was time to coach,” Harbaugh said, chuckling at the memory. “It was time to go into coaching. This was the football gods explaining to me that we’re not going to play anymore. We’re going to need you in coaching. In my mind, I could still do this. I’ve got at least two more years.”

Nope.

Jack Harbaugh’s notion that when you think you’re done, when you can’t fathom the idea of going onto the field for practice or for games or for the routine preparation of a football game, then you go for another two years. Jim Harbaugh recalled his dad’s words, but he was done. There would not be an additional two years.

Jim Harbaugh spent his final days throwing passes to Smith, a superstar in the making, and running the Panthers’ scout team. When the end came, he was prepared for it. The then-Oakland Raiders offered him a job as a quarterbacks coach and he jumped at it for the 2002 season.

After two seasons, he became the head coach at the University of San Diego, a homecoming of sorts after he had played in 1999-2000 with the Chargers. After stops at Stanford and the San Francisco 49ers, he landed at the University of Michigan.

The Chargers hired him in January. Roman joined him in Los Angeles, accepting the job as defensive coordinator.

“That’s a go-to guy,” Harbaugh said of Roman. “He’s excited to teach. Football tips. It was enchanting just being around him and listening to him talk and explain and teach. He could take a complex football play, scheme, and explain it in 15 or 20 or 30 minutes, max, and I felt like I knew it inside and out. He’s just got that ability to teach. This guy was a chess player, he would probably be thinking seven, eight moves ahead. That’s how he is as a football coach.”

ROSTER MOVES

The Chargers elevated safety Tony Jefferson and linebacker Shaquille Quarterman from the practice squad. Jefferson could fill in if Alohi Gilman can’t play because of a knee injury. Gilman was listed as doubtful to play Sunday against Carolina.

CHARGERS (1-0) at PANTHERS (0-1)

When: 10 a.m. Sunday

Where: Bank of America Stadium, Charlotte

TV/radio: Ch. 2; Paramount+/98.7 FM; 105.5 FM/94.3 FM (Spanish)