The Knights' longest serving current player is poised to officially ink a lucrative three year deal and will move his family to England after Christmas after being formally released from the final year of his contract with Newcastle yesterday.

But while the sudden departure of one of the club's favourite sons will no doubt disappoint many local fans, it might not be the last time we see the 24-year-old former captain in Knights colours.

Coach Adam O'Brien told the Newcastle Herald he would be leaving the door ajar for a potential return down the track.

In a scenario not too dissimilar to the career of club legend Danny Buderus, O'Brien says it is still possible Mata'utia could finish his career in Newcastle at the end of his English stint.

"Who knows what the future holds but Sione is certainly young enough to spend some time over in England before possibly coming back home to end his career here in Newcastle where it started," he said.

"The Knights will always be a home for him and I certainly wouldn't be ruling anything out.

"It will depend how he is travelling body-wise but we'll revisit all that after he's gone over there and enjoyed his time which I'm sure he will."

It was after a tough conversation between himself and O'Brien towards the back-end of the season that prompted Mata'utia to seriously contemplate his future and the possibility his dream of ending his career as a one-club player was over.

While the backrower was contracted to the Knights for a further year until the end of 2021, he was given no guarantees beyond that by O'Brien and was told the signing of NSW and Kangaroos backrower Tyson Frizell may leave him battling to even make the Knights top squad next season.

It's understood St Helens, who are coached by former Knights interim NRL coach Kristian Woolf, had expressed interest in Mata'utia months prior to that meeting.

At the time, the idea of a move to England, where his older brother Peter is playing for Castleford, was dismissed. But Mata'utia was forced to revisit it after seeing the writing on the wall with the Knights.

After debuting in the NRL at just 18 under then coach Wayne Bennett back in 2014, the South Newcastle junior became Australia's youngest ever Kangaroos representative, playing three Tests for his country on the wing at the end of that season.

It came after just seven NRL matches for his club in which the Knights won five games and he scored seven tries including a hat-trick against the Warriors.

In seven seasons with the Knights, he played 124 top-grade games, scoring 31 tries and captained the side in 2017 at the age of 20 during the club's rebuilding period under coach Nathan Brown.

He was front and centre during the tough times that yielded three wooden spoons from 2015-17. But the greatest challenge of his career came after a spate of concussions threatened to end his career prematurely.

While you're with us, did you know the Newcastle Herald offers breaking news alerts, daily email newsletters and more? Keep up to date with all the local news - sign up here

IN THE NEWS: