Newcastle's Jarrod Mullen and his coach Brian Smith both talked down the 20-year-old's NSW Origin prospects mainly because a leg injury could rule him out for at least a month.

Mullen missed the Knights' 30-16 NRL loss to the Bulldogs at Telstra Stadium due to tendonitis in his right calf which he has carried for the past month.

But Mullen isn't so sure the injury is simply tendonitis and will have scans to hopefully rule out a stress fracture which would sideline him for at least a month.

"It might be a stress fracture there so I've got to get scans on it tomorrow," Mullen told AAP.

"If there's a fracture they reckon about four weeks but if nothing is there I should be back next week.

"It is disappointing but hopefully the scans will be clear and I should be sweet." In just his third season of NRL Mullen is being touted as a possible halfback option for NSW in this year's Origin series ahead of Penrith incumbent Craig Gower, Cronulla's Brett Kimmorley and Manly's Matt Orford.

Mullen, who has already assumed the unwanted title of 'next Joey' following Andrew Johns' retirement four weeks ago, said his only concern is his injury and club football - not earning a Blues jersey.

"It's definitely a goal for me (Origin), but it's also a goal for me to play consistently for the Knights and continue improving every aspect of my game so I'm more worried about that first than Origin," he said.

Smith hit back at claims in a Sunday newspaper that he didn't think Mullen was up to Origin standard.

Smith said Mullen has the talent to play for NSW, but added his inexperience at No.7 and his current injury and inability to train fully would make it the worst possible environment for him to make his representative debut.

"I just feel it won't be fair on the young fella himself at the moment, given that he can't train properly, to be considered to be in what is the most pressured position in sport in rugby league at least playing halfback for a State of Origin team," said Smith.

"It is not the way to blood a young guy when he can't train properly.

"What he needs to do to make (the injury) settle is not train, not run and I would not have thought that is a brilliant recipe for a young guy to make his debut as a State of Origin player at this point in time.

"If some of the selectors see it differently and want to pick him I will be the first one to congratulate him and cross my fingers that he can get the job done."

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