Bradford Bulls back row forward James Donaldson faces six months on the sidelines after rupturing an anterior cruciate ligament.
The 20-year-old injured his knee in the win over Castleford on 12 February.
The Cumbrian, who suffered a similar injury to his other knee in 2010, faces surgery later this week.
Bulls football manager Stuart Duffy said: "It's a big blow but James has overcome this kind of injury before and has the determination to do so again."
Injury-hit Bradford were aleady without Australian centre Adrian Purtell for six weeks because of a chest problem.
And they suffered a further blow in Sunday's heavy 54-16 home defeat by Wigan when they lost their main kicker, half-back Luke Gale, with ankle ligament damage just nine minutes in.
