The Maroons' preparations for Origin III have been sent into a spin with Matt Gillett in serious doubt for Wednesday’s decider.

Gillett won’t train with the team in their second-last training session on Sunday afternoon, an opposed session with the Queensland under 20s. 

The veteran back-rower failed to finish Queensland's opposed session with Intrust Super Cup team Easts Tigers on Friday, initially believed to be because he had suffered another knock to his nose, which had been broken recently in the Broncos' loss against the Eels in round 14.

However, the team's most experienced Origin player is in danger of being withdrawn from the ANZ Stadium showdown with NSW after suffering a groin injury in Friday's hit-out.

The QRL has issued a statement to say Gillett experienced groin soreness during Friday’s field session and as a precaution was removed from the field. He has had scans and is receiving treatment.

"We will continue to provide treatment and assess his progress to give him every opportunity to play," Maroons doctor Matt Hislop said.

Maroons officials met on Sunday morning where they discussed ruling out the 30-year-old forward, but wanted to give him every chance play against the Blues, given he has played 20 Origins for Queensland.

Cronulla’s Kurt Capewell, who was a shadow forward for Queensland in the first two games of the series, will still play for Cronulla in Sunday’s match against the Broncos but could be called into the squad if Gillett is ruled out.

Bench forward David Fifita is tipped to start against the Blues if Gillett cannot overcome his injury.

The 19-year-old trained in the back row after his club teammate left the field injured on Friday.

Capewell would likely start from the bench if he is a late inclusion although 18th man Ethan Lowe is another option.

If either of them plays, it will mean Queensland will be blooding three debutants on Wednesday night with Dragons playmaker Corey Norman named to start at five-eighth and Storm prop Christian Welch from the bench.

Gillett’s potential withdrawal would be another huge blow for the Maroons who will also be without Kalyn Ponga due to a calf injury.

The experienced Brisbane forward also missed the entire 2018 State of Origin series after suffering a broken neck and playing just the first five rounds last year.