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However, the team's most experienced Origin player is in danger of being withdrawn from the ANZ Stadium showdown with NSW after suffering a groin injury in Friday's hit-out.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