David Armstrong has backflipped on an agreement to remain at Newcastle beyond 2024 and is expected to sign with English Super League club Leigh Leopards.
AAP understands off-contract Armstrong had agreed to terms on a new extension at the Knights but had a change of heart during the contract's cooling-off period this month.
In that time, Leigh approached the breakout fullback and are set to announce his signing imminently.
Privately, the Knights are frustrated by the situation, especially given they had previously attempted to open up contract talks earlier this year, only for those discussions to stall.
"Newcastle Knights have decided they will not stand in the way of David Armstrong accepting an offer to join the Leigh Leopards at the end of the 2024 season," a club statement read.
"Armstrong will play for the Knights for the remainder of the year, and we look forward to David continuing his strong form for the club."
After impressing in reserve grade, Armstrong made his NRL debut at fullback in round eight after Kalyn Ponga went down with a long-term foot injury a week earlier.
The 23-year-old played a major part in a surprise four-game winning streak without the Knights' star player.
But Armstrong fell out of favour following the big round-13 loss to Canterbury, contending with a minor quad injury after that game, and has since been usurped by Fletcher Sharpe at the back.
Armstrong has been named in the reserves for Saturday's clash against Parramatta after lining up on the wing in NSW Cup for the past fortnight.
