SHEFFIELD Eagles' coach Mark Aston has been busy rebuilding his forward pack after losing key players.
Hooker Craig Cook is the latest to make the move from crisis club Doncaster.
He will replace Andrew Boothroyd who unlikely to play again this season because of work commitments.
It follows on the signing of loose forward Peter Green and prop Michael Haley from the Dons earlier in the month.
Aston needed to patch up the pack with games ahead which will decide if the Eagles can break into the top six-play-off zone.
"We've had a string of injuries that have ruled people out for the season," said Aston.
"This is as bad as I've seen it in the time I've been coaching."
Aston hopes of extending Joe Walsh's month long loan from Huddersfield to the end of the season have been dashed because the young back row forward needs a shoulder operation.
Loose-forward Dane McDonald joined second rower Ged Cocoran and half-back Aaron Groom - both anterior crucial ligament damage - who are out for the season following surgery.
The young Australian broke his right thumb in two places in his comeback game following a shoulder injury.
The Eagles start what they hope will be a charge into the top six when they face Doncaster on Sunday - a game being played at Featherstone Rovers (kick-off 3pm) because of work on the Keepmoat pitch.
The Dons are in administration as they seek new investment and went down 70-6 to Batley Bulldogs at the weekend. It's a chance for the Eagles to avenge a shock 23-22 home defeat earlier in the season.
Coach Tony Millers is struggling after losing many of his senior players and has recruited a number of raw youngsters.
Aston said: "We have to remember that this is a South Yorkshire derby and they've got one over on us. We've got to get those points back."
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