NSW coach Ricky Stuart is set to leave Queensland guessing until 30 minutes before kick-off as to the final make-up of his side for Wednesday night's State of Origin decider.

The Blues held a crucial training session behind closed doors in Sydney on Sunday morning where it is believed Stuart let his players know just who would run out onto Suncorp Stadium in the series finale.

But the public, and more importantly the Maroons, will be kept guessing, with Stuart to take all 19 players he has at his disposal to Brisbane when the Blues shift camp north of the border on Sunday evening.

NSW's preparations have been hampered by injury concerns to Michael Jennings (ankle), Jamie Soward and Kurt Gidley (both hamstring), but all three took part in Sunday's field session to keep Stuart's options open.

Asked as to whether the players were any clearer on which way Stuart was leaning in terms of the make-up of the final 17, centre Mark Gasnier said before training on Sunday:

"It will be after today, it (training) will clarify some fitness (concerns) today and then Ricky will decide what he wants to go with and who he wants to go with.

"... it's an important session for us."

Second rower Beau Scott, who had been battling a knee injury that has sidelined him since Origin II, did not take part in Sunday's session, but NSW officials said he had simply become the latest victim of a virus that had affected a few players in camp.

With all players having seemingly proved their fitness, it appears only two question marks remain for Stuart to answer before Wednesday night.

The first is the battle between Keith Galloway and Glenn Stewart for the final bench spot - Stewart offering the more mobile option and Galloway the size desperately lacking elsewhere in the NSW squad.

The other is on the left edge, where either Jennings or Brett Morris will line up alongside Jarryd Hayne.

If Jennings takes his spot in the centres, Hayne will line upon the wing, while the Parramatta superstar will move to the centres and Morris on the wing if Jennings is deemed too big a risk.

Jennings, who hasn't played in a month after damaging ankle ligaments, was considered an outside chance at best when named in Stuart's initial 20-man squad a week ago, but has surprised officials with his range of movement as he pushes to reclaim his game one berth.

"From what I heard he didn't give himself much hope but I know Andrew (Gray) our physiotherapist has been pretty impressed with him - he's running pretty freely," Gasnier said of his possible centre partner.

"I honestly don't know what Ricky's thinking there and what he wants to do ... I hope for Brett's sake he plays but I know after today we'll be clear cut on where we're heading and who's playing and we'll be quite firmly focused when we get up there and train on Tuesday."

Brought to you by AAP © 2024 AAP