Cust only learnt he was starting against the Sharks on Thursday night but was ordered not to whisper a word to anyone outside his family.

Three days later it was impossible to wipe the smile off his face after Cust excelled in a 24-14 upset win that elevated the largely no-name Sea Eagles to the cusp of the top four.

"Great to see a young kid like Cade Cust step up. A Scone boy. A great story actually," Hasler said.

"I'm not going to tell you but you should investigate it. So you can get off your arse and do something."

And Hasler, known in NRL circles as the Mad Scientist, was right. Cust did have quite the story to tell.

When the rookie arrived in Sydney two years ago he had nowhere to stay.

Enter the great Matty Johns, Newcastle Knights legend and former NSW State of Origin and Australian Test star turned celebrity pundit and part-time coaching consultant.

"I'm good mates with Cooper and Jack, his two sons," Cust revealed outside the Shark Park dressing sheds.

"They said they'd take me until I found something. I stayed there for three months and it was footy, footy, footy. It was surreal.

"You'd see him (Johns) on the tele and then he'd be sitting on the lounge a couple of hours later.

"He is a very smart footballer. When we watched games he'd have everything to a T. He knew everything. He is so footy smart, you take as much from him (as you can)."

Cust's rise, coupled with the fine form of unsung halves Lachlan Croker and Kane Elgey and Dylan Walker's impressive return from suspension against Cronulla, has given Hasler somewhat of a selection headache.

With Daly Cherry-Evans due back in the next couple of weeks, Hasler will need to decide on a partner for the skipper.

"There's never an issue about having depth," said Hasler, who was also chuffed with Walker's comeback after being cleared in the courts of domestic violence charges.

The former Origin and Test ace was rewarded for an energetic display with an opportunist's try early in the second half that gave Manly a match-winning 20-point lead.

"He got really involved, got early touches," Hasler said.

"To score that try, you've got to be in the right position.

"I thought he was very good for his first game back."

Australian Associated Press