Outgoing North Queensland superstar Johnathan Thurston has implored the Cowboys to go harder after Valentine Holmes.

The Cowboys have already expressed their interest in bringing the Origin winger back home in time for the 2020 season, and Thurston has given the club his blessing to chase the 23-year-old.

“Val would be a great signing,” Thurston told The Courier-Mail.

“Val is a tryscoring machine and he would add a lot to our organisation, not only on the field but off the field as well.

“I’d love to see him back at the club.”

Holmes grew up in Townsville and was a dominant force during schoolboy football, although the Sharks managed to lure him away from north Queensland with a better offer back in 2013.

The Sharks, who are currently aware of the Cowboys' interests in Holmes, have put forward a long-term extension to the winger, reportedly worth $4 million over five years.

Thurston played with Holmes in the Origin arena last year, and has praised the winger's try scoring ability.

“I did a bit of work with him in Origin,” Thurston said.

“The World Cup and State of Origin has given him that self-belief that he belongs in the rep arena.

“He just has this knack of finding the tryline.”

Holmes has 19 tries to his name in the NRL this season, just two behind David Fusitu'a, who leads the league with 21.