From the outside, Jacob Hopper's breakout 2018 season looked like that of a talented young player finally able to shake the injuries and illness that marred the beginning of his career at the GIANTS.

But all was not as it seemed.

Hopper managed just 23 games across his first two seasons thanks to setbacks including facial cuts and whiplash from a pool accident, multiple stress fractures in his back, heart surgery, a broken finger and a bad ankle syndesmosis.

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Those issues were banished to the past when the tough inside midfielder averaged 21 possessions, 4.7 tackles and four clearances in 21 games last season, living up to the potential that saw the GIANTS select him with pick no.7 at the 2015 NAB AFL Draft.

The 22-year-old capped his most consistent season with a top-10 finish in the GIANTS' best and fairest.

It was a remarkable effort given the GIANT was once again forced to fight his way through another disrupted summer, after he revealed both he and the GIANTS had managed to keep one more health battle a secret.

Hopper told AFL.com.au that he was diagnosed with glandular fever just days after the pre-season began.

"It was easily the sickest I've ever been," he said.

"I knew something was wrong, I tried to come back for day one of pre-season and get going, but I was really crook.

"When we played Richmond in the prelim that year I was 89kg, then once I got sick I went back to mum and dad's in Leeton for a few weeks to rest up.

"When I arrived back to the club after that break I weighed in at 78kg.

"I couldn't eat, and I was vomiting a lot, and for about three weeks it was at its worst.

"It knocks you about and those who have had glandular fever would know it's a pretty shocking illness."

The GIANTS' pre-Christmas training phase this year lasted less than a month, but highlighting Hopper's past struggles, it was his longest stretch of work since he arrived at the club.

The onballer still has to be smart with his preparation and missed the JLT Community Series after pulling up sore from the GIANTS' scratch match against the Swans in February, but he proved his fitness in an intraclub hit-out on Saturday.

Hopper will be counted on – along with fellow youngsters Tim Taranto and Aiden Bonar, and highly-rated draftees Jackson Hately and Jye Caldwell – to take over from the experienced Dylan Shiel (Essendon) and Tom Scully (Hawthorn), and he's more than ready for the responsibility.

"I'm super excited by the challenge to step up," he said.

"Whether it's different roles or more game time, I'll accept anything now knowing I've got such a good chunk of work behind me.

"Over the past few years I've had no base, so I was almost trying to fake it to myself.

"There's areas of my game that I think I can take to another level and improve, and I'm really eager to do that.

"I really want to have more impact on games.

"I'd like to think that with more run in my legs I could play on a wing, which makes more flexible as a player.

"We've got so many boys who can run through the midfield, so we need to be able to go forward, and not only play there to fill a role, but be a really dangerous threat."