New Zealand Warriors coach Ivan Cleary today described the knee injury that has ended halfback Isaac John's National Rugby League season as shattering news.

John, 21, needs surgery after suffering ligament damage in the Warriors' gutsy 12-6 win away to Penrith last Sunday.

Earlier this year, he spent a lengthy spell on the sidelines because of a foot injury and his first NRL call-up of the season came last month when No 1 halfback Brett Seymour was struck down by a leg fracture.

Tokoroa-born John showed some good form in his five matches as Seymour's replacement, the last four of which the Warriors have won.

"It's a little bit shattering, really," Cleary said.

"He came back from a 14-week injury early in the season and he's just done an amazing job for us and continues to get better."

Cleary said no-one worked harder than John at his game.

"It's just a really cruel blow because I don't think anyone saw it coming."

John, who made his NRL debut last year and has eight first-grade appearances to his name, was set to make way anyway, with Seymour having been cleared to return to action against Melbourne in Auckland on Saturday night.

Seymour is one of four frontline players who are coming back from injury to face the Storm.

The others are fullback Lance Hohaia, winger Kevin Locke and centre Brent Tate.

Sam Rapira remains in the casualty ward, although Cleary is hopeful that the prop will have recovered from his knee problem in two weeks.

Fellow forward Jacob Lillyman has got over his foot injury and is set to turn out for the Auckland Vulcans in the New South Wales Cup this weekend.