Two months after returning from nearly two years out of the game, GIANTS key defender Jack Buckley has been rewarded for his perseverance and stunning start to 2023 with a three-year contract extension.

AFL.com.au can reveal the 25-year-old has signed a new deal to remain at the GIANTS until the end of 2026, just eight weeks after playing his first AFL game in 623 days.

Buckley underwent a knee reconstruction in July 2021 and didn't appear at all in 2022 due to complications that required multiple surgeries.

Now, the New South Welshman is the No.1 rated key defender in the AFL, according to Champion Data, having accumulated the second-most spoils in the competition after eight rounds and emerged as one of the best one-on-one backmen in the League.

That he had been sidelined for the better part of two years and wasn't even picked in Adam Kingsley's initial side for this year's season opener has made his phenomenal ascent off the canvas even more impressive.

"In my first three years on the list as a rookie, I was just surviving on one-year deals and one of my biggest issues was I didn't believe that I belonged," he told AFL.com.au.

"At the end of my second year, it was really touch and go whether I would get another contract. I am just so grateful they did stick by me.

"Once I cracked a debut and played regular footy before my knee injury, I started to get the belief that I could play at the level. I started playing back-to-back games and felt really good. When the knee injury happened, throughout the whole injury I had the belief I could play, but it turned into, 'Do I have the belief that my body will allow me to do what I know I can do?'.

"I always knew I would get back, but I would be lying if I didn't say there were doubts (about) how well I would be able to go and how well my body would be able to hold up and whether my knee would be a lingering issue for years.

"I need my athleticism and need contest stuff - that is my one wood. So if there were any question marks on whether I could jump or cut, it wasn't going to work out.

"(I'm) very grateful now I don't have any of those issues."

Buckley was initially supposed to play in a VFL practice in round one of this year before he was put on stand-by for Leek Aleer. He arrived at GIANTS Stadium with his housemate, Connor Idun, who went inside the rooms to investigate if they were playing together. It was Idun, someone who had witnessed all the challenges Buckley had faced, who broke the news that he would be making his long-awaited return.

That day is a blur, mainly due to the sweltering heat and humidity that made the GIANTS' come-from-behind victory extra memorable, but also due to the wide range of emotions Buckley dealt with in the space of just a few hours.

But what isn't a blur is his arduous expedition back to the top, which was a case of one leap forward, two steps back for more than 18 months.

The son of former North Melbourne vice-captain and Kangaroos chairman, Ben Buckley, Jack didn't just need to have his anterior cruciate ligament replaced after his left knee crumbled at the MCG in round 16, 2021. He also tore the medial collateral ligament and damaged the cartilage, making an already complicated recovery even more so.

"It was a long road back," he said.

"It hit a wall at about the four-month mark where my quad just wasn't getting any of the muscle back so I couldn't progress with any of the exercises. We had to go backwards a bit and almost started from scratch again, which was deflating. That was the end of 2021.

"When I went out and did my first run, everyone usually makes a bit of a fuss about it, so they were out there clapping. I've done a lap and knew it was feeling not great, but I couldn't go back in because everyone is out there watching. I did a couple of laps, went back in and didn't feel overly great. I had a routine check-up with the surgeon a week later and we went in for a cleanout, and went back in under the knife after he looked at the scans.

"That was the start of 2022. It was pretty minor (and) wasn't supposed to set me back much, but I ended up losing all my quad muscle again. I don't think I ran for three months after that. I started to run again and we were at the point where the graft had healed but the muscle still wasn't quite (there). One week would go right, the next I'd have a setback. It felt like I was banging my head up against a wall.

"It got to a point in June-July last year where I was starting to get my loads up but I hit another wall. We stopped running for ten weeks and just did strength work. The atrophy (reduction in muscle) was so bad after the injury, but I finally got some progress and got going from there. Ever since then it has come together. I got back into training late in the pre-season and just snuck in for round one."

Former GIANTS captain Phil Davis has been a calming influence for a long time, helping Buckley navigate the isolation and grind of rehab as well as teaching him the art of defending.

And then there is reigning Kevin Sheedy Medallist and All-Australian key defender Sam Taylor. The pair have been tight since they arrived at the club together in 2017 and loom as the long-term glue of the GIANTS' back six.

"Me and Sammy are best mates. We got drafted together, lived together for two or three years and we're very close. He has been there the whole way and seen the ups and downs of what I've gone through, especially in those early years when I was just trying to stay around," he said.

"These last couple of years in rehab, just having someone you can talk to openly (is great). He is such a loyal guy and will always try to find ways to help, to the point where I have to say 'back off' because he is so eager to help all the time. He has been great for me."

After arriving at the club as a 20-year-old category B rookie via the GIANTS' NSW zone in 2017, Buckley has lived on one-year contracts and has never able to plan beyond the next 12 months.

But now he has some certainty and security after two years of injury turmoil, he is determined to repay the faith.

"It hasn't really sunk in yet," he said.

"My first few years I didn't know how the dream was going to pan out. And then over the last couple of years I thought I would be able to sign a multi-year contract if I got back out there. Now that it has actually happened it is something I'm extremely grateful for. It fills me with a lot of pride, knowing how much work has gone into it.

"Knowing where I was when I got picked up, I'm just so grateful that the club even gave me a chance. To be honest, I was floundering around in Sydney AFL and was pretty raw at the time. I've been trying to pay them back for everything they've done for me across my career so far."