A "devastated" Jacob Lillyman has finally accepted that his playing days for his beloved North Queensland Cowboys are finally over.

The former Queensland Origin backrower will be sidelined for up to six months after being required to undergo a shoulder reconstruction.

He won't be back for the Cowboys after signing a two year deal with the New Zealand Warriors that starts next season.

The backrower from the north-west Queensland town of Richmond - where he was at one stage a real life cowboy on the rodeo circuit - has reluctantly digested the sad news.

"I feel for Jacob because obviously he's a north Queensland boy from Richmond and he's pretty devastated that that was his last game for the Cowboys," Cowboys coach Ian Millward said.

"He's very devastated that he won't play again this year, he's pretty upset.

"He wanted to go out on the right note. It would have been great (bowing out) on the last home game here but it is not to be."

Lillyman was injured in the 12th minute of last round's 48-20 loss at Melbourne.

The Cowboys were unsure whether Lillyman would begin his rehabilitation in New Zealand - as former Bronco Brent Tate did last season.

Millward said Lillyman would undergo surgery "sooner rather than later".

Lillyman, 24, made his NRL debut for the Cowboys late in 2003 and earned four Origin caps for Queensland.

He was keen to earn an Origin recall at the Cowboys after being dumped along with teammate Carl Webb following the Maroons' disappointing 18-10 series opening loss to NSW.

In other Cowboys injury news, Chris Sheppard - named at halfback to replace Queensland No.7 Johnathan Thurston - is "doubtful" and lock Steve Southern (shoulder) is no certain starter for their wooden spoon decider against South Sydney at Townsville on Saturday night.

Millward said Sheppard was battling to overcome a hamstring complaint.

"Bluey (Southern) has a lot better chance than Shep. Shep's doubtful - we'll see what transpires in the next 24 hours," he said.

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