Newcastle star Dane Gagai has likened unknown rookie Dylan Phythian to Canberra custodian Jack Wighton, labelling him one of the biggest fullbacks in the game.
Phythian will get his chance to nail down the No.1 jumper for round one when he starts at fullback in Saturday's trial against Canberra in Queanbeyan.
Gagai, who started last year at fullback before reverting back to the centres, conceded Phythian doesn't quite match up to Greg Inglis' 105 kilograms, but still had plenty of size about him.
His 95 kilograms is sixth heaviest in the league.
"He's not GI-big - that's 100-plus kilos - but he'd still be one of the biggest fullbacks. He'd be like a Jack Wighton-type fullback," Gagai told AAP.
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The 21-year-old was one of ten Knights to make his debut in a rotten season for the wooden-spooners, getting minutes off the bench as a hooker in the final two games of the year.
Gagai said Phythian had the fitness and toughness to make a fist of the fullback position, but wanted take a cautious approach before crowning him a long-term answer in the backfield.
"He's been training good at fullback but obviously training's a lot different to when you get out on the field and the boys are ripping in to you," he said.
"That's when we're going to find out what he's got. But he's a tough kid - he's quick and he's fit. I think he's going to do a good job for us, but we'll wait and see what happens this weekend.
"He's normally a five-eighth, but he's been making a red hot crack at the fullback spot.
"I think this weekend's going to be good for him, especially against the Raiders. They're fielding a fairly decent side. It's going to be good to see how he goes and how the other boys go."
Phythian's shot at fullback means Gagai will start in the three-quarter line, where he hopes to stay after spending the past two seasons switching between the positions.
"Centre's a spot I want to play in. I want to cement that spot and stick with the one position. Last year we obviously didn't have as much depth as we've got this year," he said.
THE BIGGEST NUMBER ONES IN THE NRL
Greg Inglis - 105 kilograms
Josh Dugan, Tom Trbojevic - 102
Jarryd Hayne - 100
Will Hopoate - 98
Dylan Phythian - 95
Darius Boyd - 94
Jack Wighton, James Tedesco, Roger Tuivasa-Sheck - 93
Michael Gordon - 89
Billy Slater, Matt Moylan - 88
Valentine Holmes - 87
Lachlan Coote - 84
Bevan French - 83
