The 22-year-old capped a remarkable 2020 with a game-turning debut off the bench in Queensland's 20-14 defeat of New South Wales in Wednesday's State of Origin decider in Brisbane.

The No.9 probed effectively and snuck through for the decisive try, validating Wayne Bennett's gutsy call to promote him ahead of tried and tested utility Ben Hunt in the decider.

Stuck behind Cameron Smith and Brandon Smith at Melbourne, Grant made the most of a player swap with Wests Tigers to win Dally M and RLPA rookie of the year and earn a spot in Maroons' camp.

Not selected until the final game, Grant made 26 tackles, two line breaks and constantly poked holes in the Blues' defence.

His 56-minute performance prompted former Queensland coach and player Paul Vautin to declare the No.9 jersey his for "the next eight to 10 years".

"He's 22; We saw what he did tonight when he came on," he said in commentary.

"Just brilliant. He virtually turned the game."

Grant has fond memories of Origin growing up in Rockhampton but said he wouldn't get ahead of himself after a whirlwind season.

"Going to school on a Thursday, when Queensland won it was a pretty good feeling, so that was always in the back of the mind," he said.

"It's pretty surreal, the best feeling ... something I'll remember forever.

"I can't thank Melbourne Storm and Wests Tigers enough for the opportunity ... if I did stay in Melbourne (behind hookers Cameron Smith and Brandon Smith) I wouldn't have played much footy and definitely wouldn't have been here."

Bennett was careful to give starting No.9 Jake Friend credit too, the pair even playing together as the Maroons hung on in the final minutes.

"He was very good, but Jake did a lot of work for the first 25 minutes," Bennett said.

"He was what we needed, that's the reason we did what we did (replacing Hunt to provide more spark on the bench) and he did that magnificently."

Australian Associated Press