In-form Leeds Carnegie must cope without their impressive flanker Dan Hemingway for three months after he underwent knee surgery.
The back-row has been in towering form for much of the season and been an integral part of their pack.
Leeds will be aiming for a fourth successive Championship win when they face third-placed Bedford Blues at Otley on Sunday but they must do so now minus the blindside forward.
Hemingway suffered the knee injury in the latest of those victories at Rotherham last Saturday and scans revealed he had fractured his kneecap.
The ex-Leicester Tigers forward has had an operation to repair the damage but will be out of action for up to 12 weeks.
Hemingway endured the injury in a crunching tackle that resulted in Rotherham losing possession deep in their half and ended with Oli Goss scoring the opening try of the game.
Coach Diccon Edwards has drafted Dominic Barrow into the squad for the Cross Green contest which captain Jacob Rowan believes will say plenty about Leeds’s title potential.
They could rise as high as second with victory and he added: “There was a lot of changes at the start of the season and we took our time to come together and gel.
“But we’re getting further along that line now and going in the right direction.
“We know Bedford are a very good side who look to play with the ball a lot.
“But we like to play a bit too and the fixture is going to be huge in terms of where we are in the league.
“If we win this we can go above them which would be fantastic but we know we can’t under-estimate them in any way,” said Edwards.
At the other end of the table, Doncaster Knights have a vital game themselves this evening.
Clive Griffiths takes charge of the first match of his second stint in charge of Doncaster in time for arguably the club’s biggest fixture of the season.
The Championship’s bottom club welcome Jersey, the side directly above them, to Castle Park.
Griffiths is the Knights’ new director of professional rugby brought in to assist Brett Davey.
The former Wales coach, who led Doncaster to a third-place finish in the second tier six seasons ago, has the final say over all team matters.
And he has made very few changes to the side that lost heavily at Nottingham, save for the introduction of full-back Connor Braid, who he has worked with recently while coaching Canada.