Scrum-half Danny McGuire, an ever-present this year, suffered a suspected broken ankle in the closing stages while stand-off Liam Sutcliffe sustained a knee injury and prop forward Adam Cuthbertson has a possible torn calf muscle.
Although Leeds will have McGuire’s old half-back partner Rob Burrow available for Friday’s re-match with Hull in the Challenge Cup quarter-final after he was rested on Sunday, head coach Brian McDermott is anxious to discover the extent of McGuire’s injury.
“He could have broken his ankle by the look of it,” McDermott said. “He’s not walking - he can’t even put it on the ground. It’s a bad one.
“He’s been single-handedly our best player all year and I’m not sure how we get over his loss.”
McGuire was shown a yellow card by referee Robert Hicks as he was helped from the field 10 minutes from the end for kicking out in a tackle by his opposite number Marc Sneyd.
Leeds were never behind and centre Joel Moon marked his return from injury with two of their five tries but they could never relax against a Hull side that once more belied their lowly league position.
“It was a tough win,” McDermott said. “Hull are a good team and they have been on a bit of a roll. They play a lot better than their league position suggests. We prepared for a good team and got challenged a lot.
“They are going to be a very good team at their place next week. They’re going to be full of enthusiasm and they’re going to have a huge reaction I’d imagine.”
Hull, too, have a major injury headache with ever-present second rower Mark Minichiello likely to be ruled out of the cup tie with a calf injury.
“It’s not looking good,” said Hull coach Lee Radford. “Mark has been phenomenal this season for us - along with Zeb Taia (Catalans Dragons), I’d rank him right up there with the best two second rowers in the comp this time around - so if he’s not to play on Friday, that would be a loss for us.”
Radford had no complaint over the sin-binning of Sneyd but is confident the injury to McGuire was accidental.
“It’s obvious something’s happened because I think he’s sustained a serious injury,” Radford said. “It was definitely a sin-binning for holding down.
“But if it was a crocodile roll, I don’t think he’s got that in his nature so if he’s done it, it’s probably done by accident.”
Hull scored tries through Jordan Thompson, Curtis Naughton, Danny Houghton and Fetuli Talanoa to keep them in the game and give them hope of exacting their revenge on the Cup holders on Friday.
“Our effort and commitment for each other was never in question,” Radford said. “Our skill and execution is just not giving us a chance to win games.
“We’ve got to be more clinical, that’s the frustration. We’re really having a dig but we’ve got to be better with the ball.”
Twelve-man Huddersfield put a big dent in Widnes’ top eight hopes with an impressive 30-22 victory against the odds.
Huddersfield had England forward Brett Ferres sent off after only 12 minutes by referee Richard Silverwood for punching Rhys Hanbury.
But the Giants, who trailed 10-6 at the break, dug deep to finish comfortable winners, notching four tries to two in the second half.