State of Origin | Maroons back rookie Kalyn Ponga to defend in the front line.

Queensland enforcer Jai Arrow says he won't need to play bodyguard for rookie Kalyn Ponga despite expectations the 20-year-old will be targeted in the front line of defence on Sunday.

The Maroons were incident-free at training on the Gold Coast on Thursday, with concerns Dylan Napa (ankle) and Billy Slater (hamstring) both set to feature in Sunday's must-win clash.

Ponga, usually a fullback, will debut off the bench in Sydney and Arrow expects him to hold his own against NSW's big forwards.

"He's deceptively really strong,” Arrow said. “He's showed that through the season making a lot of line breaks and broken tackles.

TEST: Kalyn Ponga and Queensland work on their defensive structure.

TEST: Kalyn Ponga and Queensland work on their defensive structure.

"He might be young but he's showed he's got a lot of class and think he'll do a great job and I'm really looking forward to him playing."

Slater hasn't ruled out moving from No.1 to the wing to accommodate the Newcastle fullback, however it is more likely he will play as a floating back-row threat and defend in the front line.

Retired Queensland great Darren Lockyer admitted Ponga would be challenged by the positional switch and expects NSW to test him out.

"There's no doubt if he's on with 30 minutes to go that NSW will probably target him if he's in the front line, because he's not used to that," Lockyer said on Thursday.

"But he's a good kid with a good attitude and will be ready for whatever comes his way."

Queensland missed 55 tackles in the series-opening loss.

"That's where game one was lost, defensively through the middle ... got busted up there a few of times," Lockyer said.

Queensland great Trevor Gillmeister, coined the Minister of Defence by selector Gene Miles earlier this week, has been in camp this week and spent extra time with Ponga in an effort to solidify the line.

Titans forward Arrow, set to come off the bench in his second Origin, said they were ready to make amends.

"They're going to try and come through the middle, so we'll have to go shoulder to shoulder and tighten up there and make those one-on-one tackles," he said.

Coach Kevin Walters named his side on Wednesday night, with Napa's spot seemingly assured after the prop got through another tough session on Thursday.

The team flies to Sydney on Friday.