Hull have confirmed that veteran centre Tony Martin will miss the rest of the season with a ruptured Achilles tendon.
The 33-year-old former Wakefield, London and Crusaders player, who is out of contract this year, has undergone surgery after sustaining the injury in last Saturday's derby defeat by Hull KR at the Magic Weekend.
Hull director of rugby Shaun McRae said: "This is obviously devastating news for Tony and the club and it's a difficult time for him.
"We had just got him back fit too after he had played a number of weeks through the pain barrier and that makes it all the more frustrating.
"He was desperate to get back and play his part this season so it's difficult for him.
"It's no secret he was coming out of contract but I don't feel that the time for that is now. We'll speak to Tony when it is more appropriate."
Hull are hoping Martin's place for the visit of St Helens on Sunday will be taken by England international Kirk Yeaman, who is back in training after missing the past five games with a foot infection.
Meanwhile, Hull have extended the loan spell of Wigan full-back Matthew Russell for a further month.
The teenager was signed by the Black and Whites to plug the gap caused by the sudden departure of Australian Wade McKinnon and has impressed in his three outings so far.