Hull winger Jason Crookes is set to be out of action for at least four months after injuring his shoulder in training.
The 23-year-old, who had just returned from a wrist operation, faces surgery before a full prognosis can be made.
Head coach Lee Radford said: "It's a real shame for him because I know he was looking forward to the start of the season.
"To suffer the injury so soon after his wrist operation and before the season starts is very cruel but it is part and parcel of our game and he'll be well looked after by our medical department."
Radford added: "It means we are now one down when it comes to filling our wing spot and that will mean another player now has the opportunity to step up and jump into that role."
The injury to Crookes comes less than a fortnight after new signing Chris Tuson was ruled out of the start of the season after suffering a back injury in training.
The former Wigan second-rower suffered the freak injury affecting a disc in his back during a routine session and has since undergone surgery.
Radford takes his first game in charge as head coach on Sunday when Hull go to Doncaster for their first friendly.
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