A well publicised pursuit of one of an exciting crop of young players at Wigan Athletic came to an end on August 10 2020 when the 18-year-old striker was unveiled at Elland Road.
Comparisons to Wayne Rooney had already been made during the England youth international's time with the Latics, due in part to his Scouse accent and the area of the pitch in which he operates.
Like his fellow Liverpudlian, Gelhardt has a naturally stocky, powerful-looking build and just like Rooney he isn't blessed with great height. Rooney Mk II was how some at Wigan described him.
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As many might have predicted, 12 months working under Marcelo Bielsa at Thorp Arch had an impact on the youngster's appearance, but few could have foreseen just how drastic the change would be.
By Christmas, there were those at Wigan who were amazed at the difference in the boy they said farewell to a few months prior.
It's the first thing Gelhardt, known universally as 'Joffy', points to when asked about his Leeds journey.
"I think I lost about eight kilograms in the year so physically I've changed massively," he told the YEP, chuckling.
"There was a photo on social media when I signed, and one with the trophy and you can see it. I think when I came in here I didn't have much information on nutrition or fitness levels, so I learned a lot."
The change in his physique did little to lessen his ability to hold off defenders and muscle his way through challenges - his balanced, bullocking runs became a feature of the Leeds United Under 23s' title-winning season.
It had benefits, too.
"When I was in the condition I was in before I came, I was running eight or maximum nine kilometres a game," he said.
"I think my average last season with the 23s was 10 or 10.5km per game.
"With the way we play man to man, in the latter stages of a game you know you've got your man fitness wise, you know you've got the better of them due to the training and conditioning. It's good. I feel good. We had a tough off-season programme, it was tough physically but if it gets you right then it's got to be done. I feel the sharpest and fittest I think I've ever felt."
Nothing good comes easy and Gelhardt, like so many before him, had his eyes opened to just how hard you have to work to play Bielsaball.
Ben White, whose development in a year at Leeds helped prepare him for not only the Premier League but a place in England's Euro 2020 squad, is among those who speak openly of how difficult murderball is until you acclimatise.
It hasn't just been Bielsa's demands that have amazed Gelhardt, but the head coach's knowledge and insight.
"It was a tough step up, physically, getting used to the fitness and tMhe manager's playing style but after a few weeks your body gets used to it," he said.
"The training sessions, just with how tough they are physically, but once you get through them you're so happy and your body feels so much better.
"I've learned so much in such a little time. Technically and tactically it's different gravy, it's unbelievable what you learn from him. It's like 'wow, how can someone know so much about football' but it's good, you really learn a lot in such a little time."
Life at Leeds is intense. On the pitch you work relentlessly, in games and in training. Off the pitch the adoration of the fans brings with it scrutiny, expectation and pressure. On and off the pitch you're always learning. Training sessions are recorded, clips are poured over by Bielsa's assistants and feedback is frequent.
In pre-Covid days, the sight of a player hunched over a laptop with a coach in the corridor outside the offices housing analysts and technical staff, before and after Bielsa's weekly press conference, was commonplace.
Gelhardt tries to retain the free spirit nature that helped him come to the attention of Leeds in the first place, while acting as a sponge when Bielsa has something to say or when he spots a first team player doing something he likes the look of.
"I'm a player who likes to play my own game when I'm on a pitch but obviously I'm still young and anything he tells me I take it and try to add it to my game," he said.
"He's a genius so everything he tells me I try to implement to my game. Sometimes it does take longer with some stuff but in the end you do get your head around it through repetition and that's what the training sessions are like.
"It's unbelievable how much you learn from [the senior pros], even just watching them play. It's a pleasure to be training and be in the same building as them, they're all top players and you learn so much day in and day out."
The most obvious example of a player he can learn from is the man holding down the number nine shirt and the lone striker role for Bielsa.
Patrick Bamford fired in 17 goals in the Premier League to earn rave reviews from fans and pundits alike. What made the 27-year-old stand out for his 19-year-old Gelhardt understudy was what he did without the ball.
"He gets a lot of praise for his goalscoring, which he's great at, but not many people see how hard he works for the team and how much he runs to get the ball back as well," said Gelhardt.
"It's a very good benchmark for us looking up and that's what we've got to try and get to, physicality wise."
When Gelhardt says 'us' he's referring to himself and strike partner Sam Greenwood, a close friend he got to know through England youth involvement over the years.
Last season they spearheaded the promotion charge for Mark Jackson's 23s, impressing up front in equal measure, and although Gelhardt made the bench for more top flight games, Greenwood got a senior debut in the FA Cup.
Unlike his pal, Gelhardt had racked up 19 Championship appearances with Wigan before arriving at Leeds, and a senior league goal to boot.
He was under no illusions that first team minutes would be harder to come by after his big move.
"When I did play for Wigan I was only coming off the bench for 10 minutes and obviously here we're lucky enough to train with the first team every day so you sort of feel part of the environment anyway," he said.
"It's the Premier League, not the Championship, so it's a bigger step up. I knew it would be tough to get in with the first team, but I was lucky enough to get on the bench a few times.
"I really enjoyed my first season here. I had a really good time, meeting all the lads, and we had a really successful season with the 23s."
Ask Leeds fans who they most want to see make a breakthrough in the season to come and Gelhardt will be among the top three names quoted back to you.
He's excited for what's to come in the Premier League 2 top tier and what might follow, if his hard work, changes and learning continues.
"I can't wait to be fair, taking on the best teams in England at our age group," he said.
"I think we'll hold our own and I think we should do well.
"With a bit of hard work, hopefully [I'll make a debut]. If I keep my head down, knuckle down and be patient and if I impress the manager, do well in the sessions and I'm fit enough, then hopefully.
"That's the aim isn't it? Maybe a few times on the bench, and to make a debut would be a kid's dream wouldn't it?"