The North Queensland Cowboys.

Johnathan Thurston's horror final season with North Queensland has continued after the side slumped to their 12th loss of the year, and even diehard NSW fans would be feeling for the future immortal.

Thurston cut a lonely figure lying on the paddock after spilling a ball minutes before full-time in Cairns on Sunday, allowing the Rabbitohs to travel down the other end and kick a match-winning field goal through Adam Reynolds.

For the past decade it has been Thurston who was the man to deliver but he is finding out late in his Telstra Premiership career how opposing sides have felt for years when the rugby league gods were not with them.

North Queensland's season is all but over after being labelled joint premiership favourites at the start of the year, when everyone feared the 2017 grand finalists who were welcoming back Thurston and Matt Scott's from injury.

It looked like the Thurston of old in the opening half of the game against Souths, but like the result, things got harder as the game went on.

Cowboys star Johnathan Thurston.
Cowboys star Johnathan Thurston. ©Grant Trouville/NRL Photos

Cowboys coach Paul Green went as far as saying the effort was not there from the side in their 21-20 loss to the Rabbitohs.

"I was really disappointed with the effort to be honest, the game was there and we had it won," Green said.

"There were a couple of plays that we didn't make that we had to. We're really disappointed especially when it was a big milestone for Coops (Gavin Cooper). To play 200 games is a big achievement.

"Really soft try on half-time and the way we started with the footy in the second half, we didn't complete a set.

"In the conditions you can't do that, we handed the game to them."

Green remained tight-lipped on the reasoning behind his side's slump, other than putting it down to basic errors.

He wouldn't even expand on Reynolds' try, where the NRL Bunker ruled Jake Granville was not impeded by George Burgess who was running through as a decoy.

"Yeah, I did [think it was a no try]. He got knocked over. I'm not allowed to talk about ref's decisions," Green said.

With the finals out of the equation for the Cowboys, Thurston left Cairns in a shattered state.

Even as Greg Inglis tried to find Thurston after the siren, the champion halfback had already made his way into the sheds.

"He takes losses in games hard anyway, regardless that it's his last year," Green said of his star halfback.

"The game was there for us, we had it but weren't able to finish it off."

Milestone man Gavin Cooper added Thurston didn't deserve the season he was having at the end of an illustrious career.

"He carries the weight of the Cowboys on his shoulders," Cooper said.

"He has for a long time. That's what has made him a great competitor. Every loss this year is hard but we keep finding ways to lose and tonight was no different.

"That 12-minute period – two minutes before half-time and 10 minutes after – you can't win a game there but you can definitely lose one. It really cost us in the end."