Newcastle Knights five-eighth Blake Green has announced his immediate retirement from rugby league.

Green joined the Knights in 2020, playing three games before suffering an ACL injury.

Green then signed with the Canterbury-Bankstown Bulldogs for the 2021 season but ultimately had a change of heart and was released by the Bulldogs to rejoin the Knights this season.

Green played another six games for the Knights this season before his shock announcement.

Speaking about the decision to retire, Green said it was the right call to make for both himself and the club.

"I can still see everything clearly on the field and know where I need to be, but unfortunately my body stopped getting there," Green said on the club website.

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"Iโ€™m always honest with myself, my teammates and our staff. It hurt, but once I knew retirement was the right call I owed it to everyone to do it as quickly as possible for the betterment of our football club."

"I want to thank all of my coaches and teammates, as well as the football staff and administrators, who have helped me live out my childhood dream."