On the top floor of USC’s newly constructed John McKay Center, the coach reclines behind his office desk and sips coffee while waiting for his next staff meeting.

It’s the second week of fall camp for the Trojans, and Monte Kiffin has just settled into his new digs, conveniently situated across the street from the practice field.

There’s a whiteboard with a handful of indistinguishable scribbles and formations, a video screen and a coffee pot, but that’s mostly it.

Though the office is sparsely decorated, a wooden 4” x 6” photo frame at least provides a fitting centerpiece. It’s a gift he received a couple years ago from his wife, Robin — although he can’t exactly recall when.

Encasing a photo of his son, Lane, on his wedding day 12 years ago, the frame is engraved with the words: “Families are the rich soil from which we grow.”

It’s the type of family snapshot that would likely be found in a number of coaches’ offices.

In this case, though, the photo is also of Monte’s boss — or as he prefers to call him these days, the “head coach.”

Monte Kiffin, USC’s renowned defensive guru and assistant head coach, has been coaching football since the mid-1960s, when he was a graduate assistant at Nebraska. He served as a head coach in college — Arkansas in the early 1980s — and as an NFL assistant. Yet now, in the latter stages of an illustrious career that’s spanned nearly five decades, he still hasn’t left the sidelines.

Instead, he has joined his son, USC’s young but polished 37-year-old head coach.

As is evident, coaching football remains Monte’s obsession. It consumes him. Even at 72, as he begins his 47th season and fourth alongside Lane on Saturday against Hawai’i, he’s as motivated as ever. It’s what he knows.

“If you ever watch The Shawshank Redemption, and Brooks Hatlen is in the jail and they let him out, he doesn’t really know what to do because he’s so used to it,” Lane says of his father. “That’s how I always describe him. He’s so used to the inner office of football and how it operates that he wouldn’t want to be outside that.”

If Monte, who works roughly 12 hours each day and spends many nights during the season at the Radisson Hotel on Figueroa Street, is in fact stuck coaching, he doesn’t appear to be bothered by it in the slightest. In a peppy voice and with a revealing grin, he still talks about the camaraderie of a football team, and about watching players grow and develop from wide-eyed freshman to seasoned All-Americans. He longs for this. It’s as simple as that.

“Coaching is when you take pride in coaching and see a player get better from his rookie year to his second or third year,” Monte explains. “It’s exciting. That’s where it’s a lot of fun. As a coach, your job is to get them better.”

υ

Making his young defense better, though, has been a prolonged process, even for Monte. In 2010, his first year in Los Angeles, the unit posted the worst statistical season in USC history, allowing 400 yards per contest. A year later, progress — if it could be called that — was slow. In late September, the Trojans gave up 43 points in a loss at Arizona State and then 41 points to Arizona, setting another school first — 40 or more points surrendered in consecutive weeks.

That prompted skepticism from the stands at the Los Angeles Memorial Coliseum to various online message boards — all in spite of his pedigree.

“Monte Kiffin’s freaking old and needs to retire,” commented one fan on the Daily Trojan’s website. “His defense is outdated, and it doesn’t work against the spread … What we need is a young defensive coordinator from the college ranks.”

With USC firmly entrenched in the second season of a two-year postseason ban, frustrations grew, and the mounting consensus among a sizable portion of the fan base became this: The son had to fire the father — a hypothetical each Kiffin insists was never discussed.

“We never really talked about it,” Monte recalls. “You have to keep concentrating, or you’ll be screwed up. You can’t coach. Oh, I’m scared to call this [play].”

Naturally, Monte toes the line between being stubborn and being confident. The architect of the famed Tampa 2 defense, he helped guide the Tampa Bay Buccaneers to a Super Bowl XXXVII championship while serving as their defensive coordinator.

“I’ve been doing this a long time,” he says. “I knew what we were doing. We were just very young. These guys wanted to do well; they just didn’t, and I take some of that responsibility. But I never really thought we weren’t going to do it. We were going to get better.”

There was little doubt, at least in his mind, that his previous success could translate to USC, which ended up winning six of its final seven games in 2011.

“I felt bad, at that time, for the kids and the head coach,” Monte recalls. “But I don’t feel bad for myself.”

υ

The father and son duo reunited three years ago. Fired by the Oakland Raiders after just 20 games, Lane quickly landed another gig, this one at the University of Tennessee. Looking to fill out his staff, he reached out to his father, who had just finished his 13th season as the Bucs’ defensive coordinator.

“It was a good situation [in Tampa],” Monte says. “So I had to think about it for a while.”

Lane, already carrying the reputation as a tireless recruiter, convinced his dad to move to Knoxville, Tenn. and to take on the same position with the Volunteers. Monte was sold on returning to a big-time college program. For as long as he’s coached, he has loved that environment: the sold-out stadiums filled with 100,000 fans, the tailgaters who wake up at the crack of dawn each Saturday, the close-knit family-type atmosphere, the pageantry of it all. He saw that in Tennessee, so he accepted the offer. Then, in no time at all, he found himself on a flight to Los Angeles after just 15 months with Lane on Rocky Top.

“We got there, I bought a home and then it’s one and done,” he recalls. “What am I doing here? I would’ve rented.”

So he turned in orange for cardinal and gold and followed his son, who had accepted the head coaching position at USC and replaced Pete Carroll.

“I didn’t really have a choice,” Monte laughs.

υ

No USC player’s relationship with Monte predates that of junior cornerback Nickell Robey.

During the summer of 2009, before Robey’s senior season of high school, he met Monte Kiffin at a camp at Tennessee, and received a scholarship offer on the spot.

Previously committed to Georgia, Robey hails from Frostproof, Fla. — about an hour and a half east of Tampa Bay — where Monte had made his name as a defensive innovator. So he knew full well about the coach’s pedigree. His late mother, Maxine, had been a Bucs fan. Robey’s cousin even played for Tampa Bay.

That is to say: A scholarship offer from Monte Kiffin carried a fair amount of significance in the Robey family.

“He was extremely well-known in Florida,” says Robey, who would eventually follow Monte to USC. “When he came to my school, people were like ’Oh that’s Monte Kiffin,’ taking pictures, things like that. I just realized how important he is.”

But no matter how important Monte becomes, his routine hardly changes. He wakes up early, drinks coffee, goes to staff meetings, talks to his fellows coaches, talks to his players, downs more coffee, goes to practice, watches film, goes to sleep, repeats the process. He’s always coaching.

“In most jobs, people work to get to retirement,” says Lane. “He wouldn’t enjoy that at all. This is what he enjoys.”

In Monte’s mind, he still has plenty of work left, too. Progress needs to be made. Though USC boasts eight returning starters on its defense and sits atop the Associated Press Top 25 poll, he insists more time is needed in order for the Trojans to build a national championship defense. So he tinkers with schemes and packages and talks to his players — he’s still concerned about their development.

“Whenever we do talk, I really can’t explain it,” Robey says. “It’s like we just know each other. Like I’ve known him all my life, and he’s known me all his.”

That is why Monte still coaches: for his players, his defensive family.

“You want to win for these guys,” Monte roars. “I’ve got two national championship rings, a Super Bowl ring, all that stuff. You know what, I want one for these guys.”

All of a sudden, he finishes his coffee, disposes his cup and then, almost immediately, pops up out of the chair behind his desk and bursts out the door to coach.

Nothing else matters.