Shaun Johnson took another step towards fulfilling his potential when the highly promising halfback signed a fulltime contract with the Warriors yesterday.

The 18-year-old has been tipped for a big future in the game and was one of five under-20 players who had their contracts upgraded. The others were promising back-rower Elijah Taylor, hooker Alehana Mara, back-rower Sione Lousi and prop James Gavet.

The Warriors often describe themselves as a development club and appear to have invested heavily in their youth with this move.

Johnson and Taylor, who are both still eligible to play Toyota Cup next year, appear the most promising of the lot but Johnson is in a pivotal position halfback/five-eighth and was a standout in helping the under-20s to the playoffs this season.

It's likely he will be mentored by controversial new signing Brett Seymour.

Johnson and the other four will join the first-grade squad when the players return to begin off-season training in early November.

Junior Warriors coach Tony Iro said all five players had the potential to become quality NRL players.

"The priority for us is developing NRL footballers so it's hugely satisfying when players take the step up like this," he said.

"They've all come on well playing with the Junior Warriors and now they've been given the chance to move up to another level. We're confident in their ability to become important players in the club's future."

Since the introduction of new youth competition last year, the Junior Warriors have produced eight NRL graduates, including the late Sonny Fai, Russell Packer, Ben Matulino and Kevin Locke. Warriors coach Ivan Cleary said the NYC initiative had already proved an unqualified success for the club.

"The competition is doing exactly what it was intended to do - develop local players into first graders," he said. "We've been thrilled with the way players have come through to make their NRL debuts."

The Warriors are still looking for a prop and outside back to complete their squad for 2010.