Not only is the karate prodigy not your average 19-year-old, he's also not your average UFC fighter – heck, he's not even your average person. No, there's something very, very different about the fighter frequently referred to as the UFC's next big thing.

The first thing that strikes you when you're talking to Northcutt is his demeanour. He'll call you "Sir" in every answer, just a touch more than he'll refer to his age – remember, he's only 19 – and he hits all the right notes when talking about the company he works for.

More than that, he's genuine when he hits those notes. The kid is genuinely honoured to be fighting for the UFC.

The demeanour is one thing but his fighting record is another. A 7-0 MMA record, 2-0 in the UFC, is nothing to be laughed at, but when you take into account that record does not include the 77 world titles – that's no mistake, seventy-seven – he was won in karate since his start in the sport at age four, it's almost unbelievable.

He'll take on injury-replacement opponent Bryan "Bam Bam" Barbarena in a welterweight bout at UFC New Jersey  in Newark this Sunday.

With a 10-3 record that includes eight knockouts Barbarena is no easy ride, but that record doesn't mean much to Sage, because he is where he has wanted to be for a very, very long time.

"When I was about nine years old, in 2006, that's when I started training the grappling, the wrestling and the jiu jitsu, everything on and off with the stand-up and the karate also so that's when I knew I pretty much wanted to start doing MMA," he said.

"When I was nine, I made the front cover of the Sport Karate magazine and they asked me what my goals were in the interview for the article and I said, and this was 10 years ago, that I wanted to fight in the UFC and now it's been 10 years and I'm getting to fight in the UFC just like I said."

Northcutt can't remember the first UFC fight he saw – he said when you watch it on TV as much as he did, specific bouts become hard to name – but he namechecked Tito Ortiz and Georges St Pierre and fighters that inspired him.

Before his second fight in the UFC, a second round submission victory over Cody Pfister, he trained with the man they call GSP at his Tristar Gym in Montreal.

He hasn't been back since, but the reason behind it has as much to do with Northcutt's intelligence as it does with his fighting.

Majoring in petroleum engineering at Texas A&M University, a notoriously difficult course to break in to, Northcutt manages to walk the fine line between fighter and scholar, for now.

"I had school and I had finals that I just finished taking before Christmas break, so I haven't had a chance to go back to Tristar but it looks like we'll be heading back after this fight," he said.

"I've actually cut back the amount of classes that I was taking so for the first semester of residence I was a full-time student taking the full classes or more, and having to do school work and be at school Monday through Friday, and Saturday and Sunday having to do group projects with my group members for engineering … there wasn't a lot of time for training. I do see myself putting school on hold in the future.

"Right now though school is super-important to me and as you can imagine engineering, particularly petroleum engineering, with the oil and gas in Texas is really huge.

"The school that I'm at is the No.1 school in the nation for petroleum engineering so it's a huge accomplishment."

That accomplishment, as impressive as it is, pales in comparison to the goal he has set himself in the UFC, to beat Jon Jones' record as the youngest champion in the history of the promotion.

"I would like to be the youngest UFC champion," he said.

"I'm only 19 years old right now, I know I still have time because I believe Jon Jones was 23 years old, so I'm still working my way up and learning as a fighter with every fight, and I think that's important."

That learning process doesn't preclude the teenager from having fun, it's just that his idea of fun is, well, a lot different to what you or I, or indeed his friends would consider fun.

Not that Northcutt would have it any other way.

"My friends are going out and hanging out with other friends and going to events and doing stuff together, well I guess it's different in my way because I'm getting to go out and have fun doing what I'm doing, getting to travel with the UFC and fight and compete with the UFC and do the things that I like to do and that's what's fun for me, if that makes sense.

"Coming into the UFC and fighting, I think it's super-fun for me, if that makes sense. I don't really have that nervousness that people have, it's more like I'm having a blast out there."

Northcutt is in the first fight of the UFC New Jersey card live on Fox Sports with Sunday, with the main event a five round clash between light heavyweight knockout artist Anthony "Rumble" Johnson and gritty wrestler Ryan "Darth" Bader.

Should be, as Northcutt would say, a blast.