Titans prop Max King has moved between the under-20s and NRL this season.

With the Canberra behemoths looming large this Saturday Titans prop Max King is desperately trying to add weight to his 19-year-old frame after illness saw him drop five kilograms prior to his NRL debut in Round 3.

‌In each of his past three starts to date King has been named 18th man early in the week only for injuries to open the door to take the field in the NRL, his debut against the Eels marking the fourth generation of King men to play first grade premiership rugby league.

Listed at 104 kilograms at the start of the season King dropped down to 99 kilograms when he was struck down by a throat infection and then thrown into his maiden game in the top grade by coach Neil Henry with just 24 hours' notice.

He has since put three kilograms back on but with the Raiders pack boasting two props weighing in excess of 120 kilograms King knows he will be at a decided weight disadvantage when he comes onto the field.

A former hooker coming up through the junior grades before a growth spurt in his mid-teens, King is still adding bulk to his young frame and is used to mixing it with front-rowers who are physically bigger than he is.

"I've got my weight back up now but there is a big weight difference but even in 20s last year I was probably five or 10 kilos under-weight for a front-rower," King said.

"But if it's a tough carry and take the hit I've just got to do it. Use a bit of footwork and find myself between the gaps of the big fellas.

"The week I debuted I had a real bad neck infection and all my lymph nodes in my neck were swollen and I was really drained through the week.

"The captain's run the week I debuted I was struggling to even get through the warm-up, I was feeling so depleted.

"Neil (Titans coach Neil Henry) knew I was doing it tough and he rang and said they were going to give me a crack and asked how my body was feeling and I said, 'It's feeling fantastic. Just give me a crack.'"

Impressing the Titans coaching staff with his attitude and work ethic during the pre-season, King has averaged 25 minutes and almost 70 metres in his three NRL starts to date and convinced seasoned first-graders such as Jarrod Wallace that he has a big future in the game.

"He's been chucked in the deep end with a lot of injuries and things like that," Wallace said.

"He played the first two games in 20s so he probably wasn't expecting to play this early but I think he's done a really good job.

"He's strong in defence and he runs the ball hard and that's all we need from a young forward. We don't need him to come on and do anything special, just do the hard yards and I think he's really done that.

"He's doing a great job and if he keeps doing what he's doing he's got a big future ahead and I'm really happy for him that he's playing some good footy and getting the chance to play first grade."

With uncertainty about his place in the top grade all year King has been attending video sessions with the under-20s squad in addition to his commitments with the NRL team so that he is ready for anything.

For the first time this week he has been named in the 17 in jersey No.16 and he admits it makes a difference with how he can mentally prepare for the week ahead.

"When you're 18th man it pretty much means you won't be playing but for three weeks in a row, to go back to back to back, it's been a massive adjustment but a dream come true," said King.

"I go to the [20s] meetings at the start of the week for a review of the game to keep up to date so if people do come back and I get sent down I'm on top of it and I know what's going on.

"It's a bit more security [being named in No.16]. When I was 18th I was still keying in on video sessions and everything but it is a bit more security that I know I'm playing here this week and not 20s."