Bulls duo Brett Kearney and Adrian Purtell will miss Sunday’s trip to struggling London Broncos.
Full back Kearney has failed to recover from an ankle injury which has sidelined him for the past three games and coach Mick Potter has confirmed he will miss out again.
Centre Purtell sustained a hamstring strain against Huddersfield on April 22 but was risked six days later against Warrington in the Challenge Cup.
He played a pivotal role at the Halliwell Jones Stadium last weekend, scoring one try and having another disallowed, but the problem flared up again.
Potter said: “Brett Kearney definitely misses out again this weekend and Adrian has a hamstring injury but I’m hoping he will be out for only a couple of weeks.
“Playing Adrian last week at Warrington was a risk worth taking but he felt a recurrence of the problem.
“I’m optimistic he could be back for the Salford game on May 18 but we’ll have to wait and see.”
Elliot Kear is moving closer to full fitness after a hand injury but John Bateman begins a three-match ban following his challenge on Brett Hodgson last weekend.
Potter felt the teenager’s punishment was harsh and said: “We’re not a team who are known for bad tackles and all of a sudden we get a grade D.
“It was an isolated incident but it’s frustrating because you can do some other stuff and cause some real damage and you get less.
“We’ve spoken about it as a group and we don’t want to see that sort of thing happen.
“It was just unfortunate that Brett Hodgson got himself in that position before he was tackled by John.”