Hull FC's Daniel Holdsworth will be out indefinitely due to the lingering effects of a concussion.
The 28-year-old half-back picked up the injury during the loss to Widnes on 2 March but played in the next two matches, before sitting out Saturday's 18-18 draw with London.
And coach Peter Gentle told BBC Radio Humberside: "It's a head injury and we have got to be very careful what we do with it. Rest is the only solution.
"It may be two or three weeks but it's something we can't put a time on.
"We're dealing with someone's health here and, as much as you can see how much we miss him, I'm not going to jeopardise someone's health for the sake of two points."
Born in Perth, Holdsworth began his career in Australia before joining Salford in 2010, and he then signed a two-year deal with Hull last September.
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