Some 60,000 kilometres of weekly road trips, a family's heartache and polish from Matty Johns have delivered Cade Cust as Manly's latest unknown NRL upstart.

Des Hasler told 20-year-old Cust he would debut against Cronulla last Thursday, but his has been a rise of serious sacrifice and mileage in the making.

Hailing from Scone, the famed thoroughbred breeding ground 250km north-west of Sydney, Cust and his family would make the eight-hour round trip to Manly twice a week when he was coming through the Sea Eagles ranks.

Behind the wheel the entire way has been mum Kasey, who wasn’t missing his NRL debut for the world, or any other occasion Cust has pulled on the boots.

Not when the memory of Cust's father Gary, who passed away when the Manly five-eighth was just 14, drives this footballing family all the way to the NRL.

"Mum, nan and pop, they drive the four hours from Scone," Cust said after Sunday's 24-14 upset against the Sharks.

"They'll actually drive straight back now as well, they're always coming down to my games supporting me.

"When I came down here for Harold Matts I was still living in Scone, so two times a week they'd drive from Scone to training which is four hours, up and back on the Tuesday and Thursday.

"My whole family would have to do that trip. That meant a lot to me, they did a lot for me behind the scenes so I owe it all to them really."

Match Highlights: Sharks v Sea Eagles

Enter Matty Johns.

When the logistics of pursuing a rugby league career saw Cust hunting for somewhere to stay in the big smoke, one of footy's most familiar faces and sharpest minds emerged.

Having played in junior sides with Johns' two sons Cooper and Jack (who are now at Melbourne and Souths respectively), Cust soon helped himself to a five-star footballing education.

"I came down to play juniors at Manly and couldn't find anywhere to stay and they said they'd take me until I found something," Cust explained.

"I stayed there for three months and it was footy, footy, footy.

"It was surreal. You'd see him (Matty) on the telly and then he'd be sitting on the lounge a couple of hours later.

"He is very smart. When we watched games he'd have everything down to a T.

"He knew everything. He is so footy smart, you take as much from him [as you can]."

Not that he could tell Johns he was getting a crack at first grade.

With Lachlan Croker battling to recover from his hamstring injury, Hasler told Cust he could inform his family of his upcoming debut, but to keep it under wraps otherwise.

"We were actually in video and Dessie kept saying 'that's your edge, Cade' but he didn't tell me it was going to be my debut," Cust said.

"I was thinking 'what's going on here?' and after he told me 'you're debuting, mate. Good luck'.

"But I couldn't tell anyone."