Off-contract Newcastle star Junior Sa'u says uncertainty over his future motivated him to a strong performance in the Knights' 24-20 win over Cronulla on Sunday.

The barnstorming centre was a menace for the Sharks all day, and showed great hands to latch onto a Jarrod Mullen pass at the start of the second half, and score what proved to be the match-winning try.

Sa'u is looking for a new deal, but Nathan Tinkler taking over as owner and Wayne Bennett as coach has cast doubt over the future of players and what they can be offered.

The Knights are keen to re-sign Sa'u and his management are in the process of negotiating.

Turning 24 on Monday, Sa'u said he's using his contract dilemma as motivation.

"Yeah definitely, ever since I first started I always kept in my head, 'play every game like it's your last'," he said.

"You never know when you're going to get injured so I just take it game by game and the good thing about me is I've still got a lot to learn and the best is ahead of me so I'm looking forward to that.

"I'm not even worried, the only focus I've got is performing well for the Newcastle Knights and let the rest sort itself out. (If) I play out of my skin, things will work out for themselves."

Sa'u turned in arguably his best performance of the year on Sunday, with a series of bulldozing charges.

He hopes his future will be sorted within a couple of weeks.

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