YORK City Knights are on the lookout for a new full-back after releasing Jordan Grayston - and a move for Castleford's York-born ace, Ash Robson, has not been ruled out.

Goalkicker Grayston, 24, who joined in the off-season from Featherstone Rovers, had been set to vie with Brett Turner for the number one spot come the start of the Kingstone Press League One season, but has now departed after apparently not sticking to "the standards the club require".

He had been named in the squad that was to face Hull FC in Sunday's friendly but the fixture was cancelled due to a waterlogged Bootham Crescent pitch and he has since been told to find a new club.

It is thought he was let go after missing training a number of times, and, with both James Haynes and Ben Dent on the treatment table long-term, it leaves head coach James Ford short of options at the back.

Ford would not confirm the exact reasons for Grayston's exit but said: "We've decided to release Jordan. He's not quite hit the standards that the club require.

"We agreed standards as a group and once they're it, they're it.

"The boys need to adhere to them consistently but Jordan's had one or two occasions where he's fallen a bit short, which indicates to me he's not the right fit for me or for York City Knights while I'm the head coach.

"I'm disappointed. I like Jordan as a person and he's got ability, but I have to uphold the standards of the club.

"I believe in rules and having a good culture and I'll do all I can to protect that, so I have to put personal feelings to one side to make sure the club continues to move forward with that culture."

Asked if he needed a replacement, Ford said: "We will be looking to bring in an outside back in the next month or so.

"But before any person comes in, other players here have moved one up the pecking order and it's an opportunity for them to show us they're desperate to play for this club."

One potential target, via a loan switch, could be Robson, the former York Acorn ARLC junior who has been impressing for Castleford Tigers in pre-season.

Ford has already tipped him for a breakthrough season in Super League after watching him give a man-of-the-match performance in a friendly against Featherstone recently, but the Tigers might first allow him to gain more open-age experience out on loan.

Asked if the 20-year-old was an option, Ford said: "He's a fantastic prospect but he's not my player. It's up to Castleford what they do with him."

Grayston finished last season in Featherstone's reserves after playing five times for Batley Bulldogs early in the year. He had played eight times for Dewsbury in 2014, having returned from Australia where he'd had a spell with Mackay Cutters in the Queensland Cup.