Two weeks ago Newcastle coach Brian Smith said Jarrod Mullen wasn't ready for State of Origin, now he can't wait to reap the benefits of the NSW selection gamble.

Smith talked down Mullen's Origin prospects a fortnight ago mainly because the 20-year-old was carrying a minor leg injury and couldn't train fully.

But with Mullen set to make his much-hyped representative debut against Queensland at Suncorp Stadium on Wednesday night after just 31 NRL games, Smith said he'd be eagerly watching his young charge and was excited about the immediate improvement it will have on his game.

Mullen and fellow Knight Kurt Gidley are two of five NSW rookies for the series-opener and Smith said his club captain Danny Buderus had told him how impressive the Newcastle pair's transformation in team camp had been.

"Bedsy in particular has been telling me he can see a change in those two boys' confidence levels," said Smith.

"I would be very surprised if they are not almost immediately better players because of this."

Smith said he expects the two Origin rookies to return with greater confidence to take control of the football team - a particularly pleasing prospect considering the Knights lost leader Andrew Johns to retirement earlier this season.

"They talk more," said Smith when asked how players improve with Origin experience.

"When they come back they tend to talk more at a club level.

"That is a reflection of confidence."

However, the big concern for Smith is whether any of his four Origin stars pick up an injury with a vital clash against Brisbane at Suncorp Stadium on Sunday.

Mullen, Gidley, Buderus and prop Steve Simpson have all been named to back up this weekend, but with injury problems already in his halves department, Smith is concerned about Mullen pulling through the torrid Origin clash unscathed.

"Mullo is the one, if anybody is going to be glued to him more than me on Wednesday night then I don't know," he said.

"(Although) I guess everybody is going to be glued to the new number seven."

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