Sandon Smith admits questioning himself following a tough NRL finals starting debut but has rediscovered his confidence after helping guide the Sydney Roosters to the last four.

The qualifying-final loss to Penrith gave Smith his first proper taste of the scrutiny that comes with being a starting halfback in the NRL, as he failed to fire in the role of Sam Walker's injury replacement in the 30-10 defeat.

Smith poked a kick dead to gift the Panthers the seven-tackle set that led to a first-half try, and put a foot into touch at dummy half as the Roosters tried to find their groove in the second half.

But it was quite a different story in Saturday night's 40-16 semi-final defeat of Manly.

Smith scored a pivotal try just before the half by dummying past Daly Cherry-Evans, and played through a cork in the second half as the Roosters booked a preliminary-final date with Melbourne.

He knew a strong performance against the Sea Eagles was the only way to silence his internal doubt.

"Is there another way? I'm not sure," Smith said.

"It was a tough ride down to Penrith last week.

"I wouldn't say I didn't let it get to me - there was questioning, there was stuff going up in my head.

"But I went to guys like Kez (Luke Keary), Cooper Cronk, Teddy (James Tedesco), those older guys and leant on them, as well as my family and the people that are close to me and mean a lot to me. They helped me through it."

Rated highly within the Roosters hierarchy, the Central Coast product is expected to succeed Keary in the halves next season after two years as bench utility and back-up playmaker.

He will have new recruit Chad Townsend to lean on, and could share halves duties with the premiership winner, but knows there will be plenty more scrutiny once he's a bona fide starting half.

"It's something you're going to have to get used to with the number seven on your back," Smith said.

"You sort of sit around all week and see things, and hear things (after the Panthers game).

"You just want to make it right, so to get out there (against Manly) and do that, it's a real confidence boost."

For now, Smith is focusing on Melbourne, having played from the bench as the Storm knocked Easts out of last year's finals by way of a late Will Warbrick try.

Smith says he's come a long way since that 18-13 semi-final loss.

"That first year in the NRL, it goes really quick. You're sort of just happy to be there," he said.

"Whereas second year now, there's that added pressure. You've been there and people expect more. I've definitely come a long way, for sure."