Doncaster finished fourth in the regular season, a place above Sheffield.
But Eagles have won the last two Grand Finals, and Cooke said: “Sheffield are favourites when you consider their experience and form.
“It’s do or die for everybody now. Sheffield are the form team in the competition, and probably the most dangerous given what they’ve achieved in the past.”
Cooke is without Lee Waterman and Mike Kelly, while Shaun Leaf faces a late fitness test.
Cooke said: “We’ve got to get the best out of the players that are playing, and if we do that then we can be happy.”
But Sheffield have their own injury problems, with Lelauloto Tagaloa ruled out for the rest of the season with a broken arm.
But coach Mark Aston will be aiming for a repeat of last week, when Eagles beat Batley Bulldogs 16-0.
Aston said: “Defensively we were outstanding. Any team that doesn’t let points in for 80 minutes is pretty special.”