On Friday night, a 1-0 fighter will battle an 0-0 fighter in an arena attached to a casino in Connecticut.

The fight is part of Bellator 185 and will probably be watched by close to a million people on Spike TV because the 1-0 fighter is Heather Hardy.

And people love Heather Hardy.

Hardy made her MMA debut in June at Bellator 180, which was by far and away the biggest event in the company’s history.

The loudest cheer of the night predictably rained down upon Fedor Emelianenko, the greatest heavyweight fighter in history, as he made his way to the cage at Madison Square Garden.

But hours earlier, Hardy earned a roar from the crowd that nearly matched the legendary Russian.

Hardy was not fazed by the reception. She wasn’t intimidated by her opponent, or the legendary arena, or the event itself. She didn’t seem to mind that her fight kicked off the night’s free-TV coverage on Spike TV, meaning that she would be the first fighter seen on Bellator’s groundbreaking night in New York City.

Hardy incessantly tugged on her green fight shorts so they wouldn’t ride up. She blew a kiss to one of her cornermen and rocked her shoulders back and forth while keeping her arms loose like noodles.

Announcer Michael C. Williams introduced Hardy’s opponent, 39-year-old Texan Alice “The Soccer Mom” Yauger, who had a 4-5 record at the time. Then Williams’ attention turned to Hardy.

The bell rang. The MMA newcomer immediately took the center of the cage. Six seconds later Hardy threw her first overhand right. The pattern of the night was set.

Everything had gone according to plan for Hardy heading into the fight.

“Like, I f—ing nailed the press conference, I nailed the ticket sales, I nailed the media, I nailed the weigh-in like a mother f—-r. The only thing I have left is the fight. I have to have a great fight. I can’t have an OK fight,” Hardy recently told The Post of the MSG fight.

“When I fight I feel like I have to show my coaches that they didn’t waste their time. You’ve got three guys teaching you different things, literally, yelling at you different things in the corner. I’m hearing three different voices giving all different instructions. One’s telling me kick, one’s telling me stop kicking, one’s yelling that I need to start moving and punch. So to make all the coaches happy with the performance, that’s what matters to me.”

Hardy had just finished a training session at the Renzo Gracie Fight Academy in Williamsburg on the kind of soupy summer day that makes all New Yorkers hate their lives. Hardy was late due to an unexpected rainstorm that paralyzed the city’s streets. Half of the class she normally trained with didn’t show up.

In one corner of the gym, civilians practiced jiu jitsu in white gis, the tradition martial arts uniform made famous in “The Karate Kid.” Ten feet away, three beefy men mulled about, made small talk and then stopped waiting. They lightly jogged around in a circle to warm up. Hardy arrived after they’d done a few laps.

Wearing a black sleeveless training shirt, black shorts and knee-high socks, Hardy plopped down her bag, hurriedly took off her shoes, apologized to all and joined the warmup. For the next hour-plus, the triad that had become a foursome boxed, grappled and practiced both how to transition from striking to wrestling and how to prevent the transition from happening in the first place.

Hardy, one of the most decorated female boxers in US history, was locked in the second she put on her boxing gloves. She sits at 20-0 and holds WBC championships in both the super bantam and featherweight divisions.

In the MMA gym in Brooklyn, Hardy didn’t think or hesitate. Her punches landed on the heavy bag with thwacks so solid it was as if they were being broadcast from a subwoofer. The guys’ gloves sounded like they were coming from tinny cellphone speakers.

But when the boxing gloves came off, Hardy’s MMA holes came to the forefront. During awkward strength training exercises that involved each fighter’s entire body weight combined with movement, she struggled. The men muscled through it. Her core — the engine room of an MMA fighter’s entire game — wasn’t at their level. It was the same thing when the group practiced transitions from striking to grappling. While Hardy’s foot speed and fluidity was next level compared to her training partners, her coach barked, “No!” each time she screwed up a move. But, at most, it took Hardy three tries before she mastered each move. It seemed second nature after that.

Inside the cage with Yauger, Hardy went to her boxing early and often.

Stepping in hard with her front foot, she smacked Yauger with crisp left jabs before unfurling her overhand right.

The simple 1-2 didn’t work at first. Yauger closed the distance, clinched, and either went for the takedown or slammed a knee into Hardy’s midsection. Body shots are as effective as they are unsexy. They straight-up hurt and slow fighters down.

Hardy took Yauger’s knees without blinking. She bled from a cut above her left eye and continued to push forward with her right hand tucked under her chin, ready to be fired.

Through two rounds Hardy was probably in the lead, but it is possible they had given at least a round to Yauger because both had inflicted significant damage on the other.

Both women were also a bloody mess.

Hardy is not like most modern MMA prospects. She did not start training as a teenager: practicing her wrestling, jiu jitsu and striking.

In fact, she only started training as a boxer in 2010. At the time Hardy was a 28-year-old single mother living with her sister, Kaitlyn, also a single mother.

Sensing Hardy’s life was a grind, Kaitlyn got Heather a little present: a gift certificate to the gym that had just opened down the street. Heather took a yoga class then started doing cardio kickboxing. A few weeks later she won her first kickboxing match. Two years after that she made her professional boxing debut. In 2013, just three years after her first class, Hardy won the UBF International Female Super Bantamweight Title.

She has never lost a professional fight and has a well-earned reputation for putting on a show. Hardy does not mind getting hit and has been knocked down on multiple occasions, but inevitably gets up and comes at her opponent harder than before.

Hardy’s unerring drive to succeed inside the ring is only matched by her commitment and authenticity outside of it.

Hardy talks about how hard her life was growing up in the heavily Irish neighborhood of Gerritsen Beach. In profile after profile, from Vice to Rolling Stone, she speaks about how she was raped by a neighborhood friend when she was 12 years old. She tells the story about being with her high-school sweetheart for 16 years, how they got married and she got pregnant when she was 22, and how she didn’t want the baby. She kept the baby because, according to Hardy, that’s what people do in her neighborhood. The marriage didn’t last, so Hardy built herself a new, two-part life: one part fighter, one part fierce mother to now 13-year-old Annie.

However, the eye-catching details of Hardy’s personal story do not capture the endearing contradiction that has turned her into a women’s combat sports star. Hardy is self-aware without being debilitated by either self-doubt or arrogance. Everyone, from promoters to trainers to her clients — she works as a boxing trainer at the legendary Gleason’s Gym, where she also trains — lights up when asked about her, yet none mentions her fighting skill.

“The most important thing to find is heart,” Nick Skerlic, Hardy’s MMA striking coach, said, his voice rising in excitement. “She’s showed the most heart I’ve ever seen.”

In a sporting world dissected by talking heads and picked apart by Twitter, Hardy’s sense of well-being somehow still shines through in the shallowest of moments. At the ceremonial weigh-ins before her Bellator debut, she walked out in an extremely low-cut, black one-piece bathing suit, matching black hipster glasses and blazing red lipstick. She was going for “classy yet sexy.”

“There are a lot of ways of making people remember you. I have to make people remember me,” Hardy said. “Something stupid like these ridiculous glasses, black bathing suit and red lipstick, people remember that.

“I have to do something different, I have to make people remember me. Typical sports bra, ponytail, like, it’s been done. You want to make a statement. That’s what fighters don’t understand. A good fight is only one piece of a really big puzzle.”

Another part of that puzzle is that fighters at this level often have ticket-sales obligations. For her first ever boxing match, her promoters wanted her to sell $10,000 worth of tickets. She sold $13,000 instead, according to ESPN. For her Bellator debut at MSG, Hardy said she sold $25,000 worth of tickets.

“I didn’t have to sell any tickets, I wanted to. The ticket lady was like, ‘f–k,” Hardy says with a laugh before getting serious again. “Like, I don’t do it for the admissions, I do it so they know that I hustle.”

The drive, the hustle, the will to win — whatever you want to call “it,” Hardy has it.

Yauger was visibly drained as the third round began. Her movement slowed, her hands dropped, and Hardy dragged her into the deep end by pushing the pace.

Jabs, overhand rights and inside leg kicks all landed, but the zip was gone from Hardy’s strikes. If she was going to win, she was going to win on points.

With about a minute left to go, the two women stepped in to throw punches at the exact same moment. Their fists didn’t find their targets. Instead, skull crashed into skull and a huge cut opened above Hardy’s left eye.

Referee “Big John” McCarthy immediately called time and motioned for the doctors. Blood poured down Hardy’s face, but she was deemed fit to continue.

Even brief stoppages can ruin fights. Momentum stops dead in its tracks, judges have time to overthink things and adrenaline dumps can have unpredictable effects on fighters.

Yauger seemed to get an energy boost during the break. She took the center of the cage and attacked as if she hadn’t just fought 14 tough minutes.

Hardy took Yauger’s strikes, circled left, then right, planted her feet and slammed a beautiful 1-2 into Yauger’s face. “The Soccer Mom” stumbled back, seemed to regain her feet, and rocked forward only to meet another Hardy 1-2.

Yauger fell to the canvas and scrambled to get back up. Hardy stood still. She didn’t rush in. Instead, she waited for Yauger to get upright so she could let her fists fly.

A hurricane of clean punches later, McCarthy stepped in to protect the now defenseless Yauger.

With just seconds left in the third round, Hardy earned a spectacular knockout victory.

After seven stitches to the face, Hardy sat at her post-fight press conference a picture of contentedness.

“I’m so happy right now, I don’t even care that I have stitches in my face,” she effused between laughter. “I think I just fell in love.”

Hardy translated that love into a two-year contract with Bellator that guarantees her at least four more fights with the promotion, according to MMAJunkie. Her next fight is against newcomer Kristina Williams at Bellator 185.

However, back in the summer, Hardy was still negotiating her new deal, and her coaches were still focused on the past.

“When she got cut, most guys I would tell them to lay back because you’re winning the fight,” Skerlic said. “But she has so much heart, she just went out and knocked her out.”

For Hardy, the cut was a turning point.

“Everything goes out the window, all the doctors are looking at you. They’re checking to see if you’re medically and physically OK. So I have to show them that I’m here to fight,” Hardy said.

“Balls to the wall, I had no choice. I had to leave everything out there and go after this girl and show them that I’m still in the fight.”

Hardy showed them that she was more than still in the fight — she was there to win, and win convincingly.

“I sacrificed so much for this fight,” Hardy said, “Getting a babysitter, paying for a babysitter, not spending time with my child, not being there when she gets home from school, all of these things are going through your head. I’m not going to lose. I invested too much in this fight, and too many people are here cheering for me, rooting for me, my whole career is on the line.”

That sentiment was doubly true for her coaches.

“Everything is teachable and I’m proof of that,” Hardy said, deadly serious. “I’m the most retarded person on the planet and people are like, ‘You’re so talented and athletic.’ I am not!

“I learned how to do everything. The only thing I didn’t learn: I’m good at getting punched in the face, I’m really really tough and I never get tired. I never get tired of fighting.

“To make all the coaches happy, that’s what matters to me.

“I don’t know that I’ve ever made three men so happy at the same time,” Hardy cracked wise as the gym erupted in laughter.