O'Sullivan prepared to step in for Cleary

After playing for Penrith for the first time since he was a Year 12 student, Sean O'Sullivan is prepared to deputise for Nathan Cleary in round one of the NRL season if the star playmaker isn't fit.

Cleary has started contact training after off-season shoulder surgery but the Clive Churchill medal winner is no certainty to feature in the season opener against Manly on March 10.

With the composed O'Sullivan as back-up, the Panthers don't have to rush Cleary.

O'Sullivan produced a strong performance in Sunday's 34-6 trial win over a young Cronulla side, having a hand in two tries before resting for the second half.

"Nath is on his own timeline and if he's not ready I'll be ready to go," O'Sullivan said.

"If he is ready, I'll be supporting him 100 per cent because he's the best half in the competition.

"It's been awesome being able to learn off him. He's had so much time for me. We watch training together afterwards and hang out."

Starting in Penrith's development system in the under 12s, O'Sullivan made his NRL debut for the Sydney Roosters in 2018 before stints with Brisbane and the Warriors.

It's been a career of perseverance, the 23-year-old having already fought back from three ACL tears.

After playing 12 games for the Warriors last year before a first injury-free NRL pre-season, O'Sullivan shapes as a more than capable replacement for Cleary or five-eighth Jarome Luai.

"I took a lot of confidence from playing the most games in grade that I've played (in 2021)," he said.

"Hopefully, I can bank on that this year and take some confidence into whenever I get a shot to play NRL knowing that I'll be ready."

Returning to the foot of the mountains has been smooth.

"I've grown up with all these boys," O'Sullivan said.

"We all