Leeds winger Ben Jones-Bishop has been ruled out for up to six months due to a blood clot in one of his lungs.
Jones-Bishop, 24, was diagnosed with a pulmonary embolism during pre-season training and has been advised to avoid all contact for three months.
He said: “I am looking forward now and doing everything I can to get back as soon as I can, once I am given the all clear.
“It is a relief to get it diagnosed and get treatment and to know that it is not a life-threatening condition.
“Generally I am in good health but as a sportsman you need to resolve these issues as soon as possible to make sure that you can perform to your maximum.”
Head Coach Brian McDermott said: “It is a real shame for Ben that he will miss the start of the season.
“He finished the season in great form and was a big player for us in our big games last season.
“We have no major long-term concerns this will impact on Ben’s career and he will receive the best possible care to make sure the issue is resolved and he can resume playing.”
His place in the Leeds side could be taken by Joe Vickery, who recently signed a one-year deal at Headingley after a successful trial spell.