CLEMSON, S.C. — It’s 80 degrees in the shade in Clemson, above 90 under the lights, and Kirk Herbstreit is sweating. This in itself is not surprising: Herbstreit, the star of ESPN College GameDay, is a sweater. He sweats in Clemson, as do most; Herbstreit also sweats in October, sweats in Big Ten country, sweats in December, sweats rain or shine.

But it’s Clemson, humid and muggy Clemson, and the weather isn’t cooperating. So the sweat drip-drips, collecting on his brow, leading Herbstreit to use whatever means necessary to corral the misbehaving moisture.

He improvises. Installed in the inside panel of the main GameDay set is an air-conditioning unit. Herbstreit bends down and puts his face up against the vent, resembling a submarine captain peering through a periscope. He uses wad after wad of paper towels, patting his forehead after each break. He downs gallons of bottled water.

He also gets some help. ESPN gives each of its male hosts – Herbstreit, Chris Fowler, Lee Corso, Desmond Howard and David Pollack – use of an ice vest. The contraption, which fits snugly between skin and clothes, runs from a hose streams of ice-cold water around the wearer’s torso.

Yet it’s 9:30 a.m. Saturday, and despite the improvisation and the help, Herbstreit is sweating.

“Kirk’s a sweating machine,” Howard says. “He’ll sweat in December.”

He looks toward Herbstreit’s seat on the main set, empty, with Herbstreit filming a segment on ESPN’s demo field, built to the left of the set. “He’s miserable,” Howard says.

It’s not getting any cooler – in fact, it’s getting warmer by the minute. The crew is 30 minutes into the broadcast. Did I mention GameDay is four hours long?

***

GameDay is entering its 27th season altogether and 21st year filming live on the scene of college football’s marquee game of the week – and it continues to grow in popularity. The live broadcast, the first course of ESPN’s all-day, all-college football buffet, draws thousands of fans to the set and millions more on television, making it one of the network’s gold-standard programs.

From the outside looking in, from the couch in the den, the program is a masterwork in precision. Fowler is a flawless conductor, feeding his co-hosts during set pieces and seamlessly bridging the broadcast from segment to segment. Herbstreit is widely viewed as the most trustworthy and respected television analyst in the sport. Corso has developed a cult following. Howard, the 1991 Heisman Trophy winner, gives the main team another believable voice.

Behind the scenes, however, GameDay is propelled by an orchestra of technicians, cameramen, producers, directors, set designers, stylists, crowd pumpers, handymen, drivers and security guards. The show itself, so watertight in its execution, is built, developed and maintained during the course of several days of preparation.

ESPN gave USA TODAY Sports an all-access glance at what makes GameDay tick, from the first moments on the ground to the final seconds of the broadcast. This weekend’s show lasted four hours; at least 72 hours went into its creation and execution.

***

It started Thursday morning when an ESPN caravan descended on Columbia, S.C., where No. 6 South Carolina was playing host to North Carolina. In overwhelming heat, ESPN’s background crew prepares for a 6 p.m. kickoff – with Rece Davis, Jesse Palmer and Pollack in the booth and Samantha Ponder working the sideline.

Broadcast trucks litter the parking lot. One is the nerve center of the entire operation, the production truck, housing the game’s producer and director. Another contains the team responsible for culling together replays. A third truck produces the telecast’s secondary show, College Football Live, which is filming on the field at Williams-Brice Stadium.

Scott Van Pelt, Mark May and Lou Holtz film at 3:30 and again at 5, with the latter serving as the pregame kickoff. They go through segments and break for commercials. During commercial breaks, May drapes a wet towel over his head, like Lawrence of Arabia, soaking himself in cold water. Van Pelt leans back and opens his suit coat, revealing a white shirt soaked to the bone – it turns out the ice vests have yet to join the crew.

Holtz is unperturbed, dry as the desert, and swivels in his seat as his co-hosts dream of glaciers. “You can’t get water from a rock,” Holtz says. “Maybe Moses could do that. Only spongy people perspire.”

Up in the booth, Pollack prepares for a loaded weekend: He begins in Columbia on Thursday, moves to Clemson on Friday and Saturday, drives home to Athens, Ga., and then flies Sunday to Pittsburgh, where he’ll call Monday’s game between the Panthers and Florida State.

The plan is simple: Pollack will call the South Carolina game, which will end before 9:30, before tripping to Clemson to prepare for GameDay. The television crew – dozens of people, with tasks ranging from electrician through producer – will follow suit. A portion of the crew will even go ahead early, getting to Clemson in time to begin preparing the set for Saturday’s GameDay broadcast.

The weather has other plans. An arid and steamy evening quickly turns. Lightning flashes through the sky about midway through the fourth quarter, delaying the game with eight minutes left to play. Individual schedules are dashed – more importantly, perhaps, ESPN’s television schedule is thrown askew. Mississippi and Vanderbilt was set for a 9 p.m. kickoff. South Carolina leads UNC 27-10 in a game no longer in doubt but still unfinished.

Affiliates are alerted, schedules consulted, changes made. The Rebels and Commodores will air on ESPN as scheduled. The Gamecocks and Tar Heels, when they retake the field, will air on ESPNews. Crisis averted, to a degree, but the GameDay caravan has been delayed. The heart of the crew still gets to Clemson on Thursday, later than expected, and faces the specter of little sleep before approaching GameDay setup early Friday morning.

***

The on-camera talent arrives Friday morning en masse: Herbstreit enters, as does Brent Musburger, Fowler, Corso and Howard, joining Pollack and Ponder. Each has obligations on SportsCenter, beginning with Musburger, who tapes a live piece at 9 a.m., followed by Howard two hours later.

But the work starts before dawn. The GameDay set will be created on Bowman Field, a wide swath of grass outside Holtzendorff Hall, one of the oldest buildings on campus. Trucks roll off the street and onto the field, loaded with electrical equipment and the bones of the set’s various installations.

There’s the main stage, which includes the central hub of the show, the four-seat dais for Fowler, Corso, Herbstreit and Howard. There are three main cameras to install; two monitors for the cast to follow the show; nine primary lights and, befitting Saturday night’s matchup, two helmets: Georgia and Clemson.

The demo field is set to the left of the main stage, bracketed to the west by a Coke Zero installation, a newcomer to the GameDay environment; to the north by an outcropping of crowd area; and to the south by a big-screen television – think the one on your wall, and then increase the size a hundredfold. Another screen stands to the right of the stage, behind an eating area for executives, sponsors and friends.

Minus one or two missing nuts and bolts, the entire setup is created before noon, when the primary broadcast team – the hosts, the producer, the director – meets for its first of two production meetings.

The meeting’s underlying question: How do we create a four-hour broadcast? The primary GameDay broadcast has long spanned two hours, from 10 a.m. through noon. In the past, ESPN has aired a one-hour pre-show on ESPNU, though often led by a different cast. This year’s program will be three hours long, beginning at 9 a.m. – this Saturday’s show will run until 1 p.m., when ESPN will flip to College Station, Texas, for Texas A&M’s game against Rice.

Dealing with the extra hour is one question on the table. Another: What do we do about Johnny Manziel? Manziel, last year’s Heisman Trophy winner, was suspended for the first half of Saturday’s game due to a violation of NCAA rules. He has dominated the national conversation throughout the offseason – if not since last November. Does that mean he should dominate GameDay?

The program is scheduled down to the minute – to the second, in fact. The first segment will run from 8:59:46 to 9:11:06, with more than a minute set in place for ESPN correspondent Mark Schwarz, who will appear live from College Station.

“Here’s what I want to guard against: I don’t want to become Manziel mania for four hours,” GameDay producer Lee Fitting says. “I know we won’t. But at the same time, people want to hear, ‘Hey, it’s the first big day of college football.’ Maybe one person hits on it and the rest talk other stuff.”

Herbstreit asks, “Is it more about today or the season, who replaces him?” Adds Howard, “Can’t bring it up unless you’re going to go in.”

There’s a worry of Manziel fatigue. “I just feel like, maybe I’m wrong, but our viewers … I just feel like if we dove into Manziel, it’ll be like, ‘Ah, here we go again,’ ” Fitting says.

The topic is tabled, exchanged for another segment, which is a theme: The production meeting rolls over the minutes of the program like a UN summit, but the plan, in a sense, is to be unplanned. “We’ll have different conversations about him as we go,” Fitting says.

The minutes provide the backbone of the telecast. But Fitting, Fowler, Herbstreit and others have been here before, through a hundred-plus telecasts; the program is extremely comfortable playing things as they come, putting topics in pencil and allowing for spontaneity – an obvious goal for Fitting and the cast.

“It’s the most unscripted scripted show on TV, in my mind,” Fitting says. “We map everything out and we get off the rails, and we realize it’s OK to get off the rails. You want to get off the rails. If you stay on the rails, that’s more of a problem. But you want to get off the rails.

“It’s so rare on TV where you can get a great moment,” he said. “My mentality is when you get a great moment, milk that moment. Which doesn’t happen in TV that often. I want the guys to be like, ‘Get me off the rails as soon as possible.’ ”

By the end of Friday night, after another production meeting, the show is locked into place.

“When we leave Friday, the hay’s in the barn,” Fitting says. “We could do the show at midnight Friday if we had to.”

All that’s left are a few small things. “The guys are still writing, going over their thoughts,” Fitting says. “But in terms of what I do, I’m in a good spot. I try to make it when I leave here Friday night we’re ready to go.”

***

Fitting raised the stakes during Friday’s meet-and-greet with local media. “If this isn’t an all-time GameDay crowd I’d be disappointed,” he said.

Hundreds of Clemson fans – and a smattering of Georgia fans – were on Bowman Field at 5:30 a.m., hours ahead of kickoff. Some came right from a local bar, perhaps: Bars in Clemson mostly close at 2 a.m., but more than a few close at 4; conceivably, one could have closed down a bar, grabbed a sandwich and strolled to the set, getting there in time to take up a prime position.

Well, getting there early doesn’t matter. Room in the main crowd area, one directly behind the main set, is not necessarily first-come-first-served but given to the elite – it helps to get on set early, of course, but there’s always room reserved for those with the proper lungpower and the best GameDay-centric signs. You know the signs: ESPN puns, jokes, taunts – but all within the range of good taste.

There are certain crowd rules: No food or drinks, no vulgar signs, no throwing objects, no religious signs and no political signs, among others. ESPN’s security team culls through the signs, removing one for every five that pass muster. One that doesn’t make the cut: “Mark Richt farts in public.” Several Miley Cyrus-related signs do make the cut.

Paul Finebaum, the newest member of the GameDay cast, films a piece at 7:30 a.m., while Pollack and Ponder do the same at 8. At 8:45, the on-camera crew begins taking its place on the main stage – Corso receives the loudest cheers.

In the main production truck, Fitting and director Tom Lucas count down until airtime. Fitting is fired up: “Let’s have fun with this. If we’re not having fun, they’re not having fun.”

He adds a word of caution to the crew, with tongue in cheek. “Don’t get tired halfway through like (South Carolina defensive end) Jadeveon Clowney the other night.”

It’s 9 a.m., and GameDay is on. Four hours to go. The four hours go by without a hiccup.

***

What’s striking is the dichotomy among the preparation, the work behind the scenes and the eventual execution. Frenetic work in the production truck is tempered by smooth performances from Fowler, Herbstreit and the cast. Off camera, crew members like Mike Pacheco run from station to station, one moment coordinating Pollack’s move from the stage to the demo field, the other throwing hands in the air, cajoling the crowd into a frenzy as the show comes out of a commercial break.

All the camera shows is a shift from commercial to scene: Clemson is excited for GameDay. Fowler is fed direction from Fitting and Lucas, and he swerves and moves adeptly, leading the cast by example, a general in wartime.

Even the scripted seems unscripted. During Friday afternoon’s production meeting, Fitting and Fowler had discussed how to use a map feature detailing the short trip from Athens to Clemson. Fitting suggested that Fowler go through the turn-by-turn driving directions; Fowler takes this tack, providing one of the show’s funniest moments.

No scripted moment – well, somewhat scripted moment – seems more on-the-fly than Corso’s end-of-program highlight: Corso caps every broadcast by picking the winner of the day’s marquee game, capping his pick by donning a mascot-related headgear, or some other team-centered paraphernalia. (But even Corso has his limits: Asked Friday if he’d use a live tiger if he picked Clemson, Corso replied, “Absolutely not.”)

The man in charge of the end-of-show headgear and props is Joe Andreasen – nicknamed “Tree,” for reasons unknown – who calls himself Corso’s personal mascot-head assistant.

He usually knows Corso’s pick by Wednesday, giving Andreasen ample time to corral the necessary prop; this week, Andreasen knew the pick by Thursday night, and GameDay had the prop – a pair of bulldogs, for Georgia – set up by Friday.

“Sometimes we might get both of them,” Andreasen says in case of two scenarios: Corso might change his mind, for one, but Corso also likes to rope-a-dope the crowd into thinking he’s picking one team before ultimately opting for the other.

“A lot of times, he might do the fake. Let’s say he’s picking Clemson, he might talk about Georgia, how he loves that ugly dog, then he goes, ‘But forget it,’ and I’ll give him the Clemson head.”

It takes a degree of sleight of hand to get the prop or headgear on stage without tipping off the nearby crowd. Saturday’s prop are bulldogs: Prissy, a girl, and Man, a boy, supplied by a Georgia pastor, Glenn Lyles.

The bulldogs, just puppies, need to be kept cool, covered and protected. A plan is devised: Andreasen and Lyles will get a cardboard box, a moving blanket, ice and water, and surreptitiously bring the two puppies on stage during a commercial break before the final segment. Lyles will crouch behind the feet of Herbstreit and Corso, under the blanket, cradling the two puppies. When Corso makes his pick, donning Georgia headgear, Lyles and Andreasen will put the larger of the two bulldogs, Prissy, on the table; Corso will hold Man in his arms. It works – even as Prissy falls asleep on the table.

But Corso’s pick of Georgia over Clemson angers the Tigers faithful. The crowd, once firmly on Corso’s side, turns negative, cascading a parade of boos as the production crew counts down the final seconds of the broadcast.

It’s part of the game, Corso said. “Fifty percent of the people are upset,” he says. “I’ve pissed off everybody in America.”

Fitting was pleased with the quality of the broadcast. “It used to be we’d leave the first week and I’d say, ‘Not bad for Week 1.’ Not anymore,” he says.

“These guys were in midseason form.”

***

GameDay has become a celebrity in its own right – the show, driven by celebrities, has become one of the flagship programs across the ESPN networks. College football has quickly become one of the most popular sports in America; GameDay is the sport’s defining program.

“Because of what the four guys have done in their popularity, it’s become one of our signature shows,” Fitting says. “It’s nothing about what I did, it’s what the guys have done and their popularity, passion for the sport. It’s sort of the kickoff to one of our biggest days of the week, Saturdays. I believe if you took College GameDay away from Saturday, there’d be an enormous void.”

He’s right: GameDay has become part of a routine for fans of college football, serving as the entry point for a day’s consumption – for a season’s consumption, as a way to connect new fans to the sport, old hands to today’s news, putting its finger on the sport’s pulse. As important as GameDay is to ESPN, in terms of the setting it creates for the network’s day-long slate of telecasts from around the country, “it’s crazy what the show means to the fans now,” Fitting says.

“It’s college football hardcores. It’s a way of life. It all stems back to the raw passion the guys on the set have for the sport. Nothing’s contrived. Nothing’s made up. It’s natural. It’s special because of all that.”

As such, every decision the broadcast makes has to be handled with kid gloves. “You can’t just do something to do it,” Fitting says. “The brand has gotten so big. It’s a traveling-circus atmosphere. I came out here (Friday night) and just looked and said, ‘Oh, my God.’ From where we were 10 years ago to where it is now? It’s crazy.

“Every year it gets bigger. And you hope it gets better every year when we add people here and there. Yeah, I understand the importance of the brand to the company and the sport and the fans. The biggest thing for me is that every decision is sort of a group effort. From our bosses and our management team to guys on the set, to guys behind the scenes. People that have made the show have to be involved in that. One of the reasons we’ve had success is that everybody’s included. Everything is a team deal.”