"It's a very big blow, because Matt had been in excellent form," said the Eagles' coach, John Kear, who must decide between Lynton Stott and Neil Law to fill the gap for today's home game against Halifax. If Law plays, it will mark a first-team debut for the former Northampton rugby union centre.
Kear is also without Paul Carr and, almost certainly, Rod Doyle, and must choose between Dave Watson and Gareth Stephens at stand-off against a side which is proving as big a surprise packet in Super League as did Sheffield in the Challenge Cup.
"I'm not that surprised, because Halifax have recruited very well," Kear said. "Gary Mercer is being played exactly as he should be and Gavin Clinch is a very good player."
The match is doubly important for Sheffield after last Saturday's last- minute defeat by Leeds in circumstances that still have Kear fuming. He believes that the video of the match proves that the referee, Stuart Cummings, was wrong on two counts to award the penalty that won Leeds the match.
"But I have banned the players from talking about it. We have to be completely focussed on this match now," Kear said.
In tomorrow's programme, Leeds have the opportunity at St Helens to equal their best start to a season for more than 30 years, if they can win their eighth game on the trot.
"There will be added pressure on the whole squad," said Leeds' Paul Sterling, who, along with the unfortunate Crowther, has looked one of the canniest wingers in the competition.
"We are top of the league and every club wants to knock us off, but I believe that every player is playing at the top of his game. Everyone is doing that little bit extra for each other."
For Saints, their second row Paul Sculthorpe has been cleared of a cracked sternum but is still rated doubtful.
Wigan must maintain the pressure on Leeds by winning at Hull. Tony Smith's knee injury gives Darryl Cardiss his chance at scrum-half after seeming set to move to Bradford a couple of weeks ago.
John Monie opted instead to let Rob Smyth go to London - something he might have been reluctant to do if he had known that Wendell Sailor was not coming - and Cardiss' versatility will be put to the test at the Boulevard. He has played wing and full-back for the first team, but scrum- half is probably the 19-year-old's best position.
Simon Haughton is preferred to Mick Cassidy for a starting spot in the second row, but there is still no place for Terry O'Connor, despite the club telling him this week that he is still wanted at Central Park.
Warrington try to keep their encouraging run of three victories going at point-less Huddersfield, although they must do so without the injured Mark Forster and Brendon Tuuta.
Salford, with Andy Gregory exiled to the stand for the first time, face Castleford without Steve Blakeley who has had concussion.Reuse content