The injury is set to ruin Fusitu'a's hopes of turning out for Tonga in the mid-season Pacific Test against Samoa in Sydney next Saturday, with Kearney saying it was "very unlikely" he'd recover in time for the match at Campbelltown Stadium.
Fusitu'a has been in top form throughout the first half of the season, with his hat-trick of tries against the Sea Eagles putting him three clear at the top of the NRL's top tryscorers list with 15 four-pointers so far this year.
Kearney hopes Fusitu'a will be back on deck for the Warriors' next home game against Cronulla on June 29, following next week's stand-alone representative weekend.
"I anticipate that but it's hard to say," he said.
Fusitu'a's absence comes just as the Warriors welcome back captain Roger Tuivasa-Sheck from an ankle injury that kept him out of last week's game at AMI Stadium.
Tuivasa-Sheck came through today's session unscathed and is in line to play his first game since departing play late in the round 12 loss to South Sydney at Mt Smart Stadium.
The Kiwi international's comeback allows backline utility Peta Hiku to return to centre after switching between fullback and five-eighth in the Warriors last three matches.
Back-up halfback Mason Lino was the other player scratched from the Warriors extended 21-man squad named on Tuesday.
Meanwhile, reserve centre Justin O'Neill and second-rower Mitchell Dunn are the two players trimmed from the Cowboys extended bench.
Cowboys v Warriors at 1300Smiles Stadium, Friday, 8pm
UPDATED TEAM LISTS:
Cowboys: 1 Michael Morgan, 2 Kyle Feldt, 3 Enari Tuala, 4 Kane Linnett, 5 Javid Bowen, 6 Te Maire Martin, 7 Johnathan Thurston (c), 8 Matthew Scott (c), 9 Jake Granville, 10 Scott Bolton, 11 Gavin Cooper, 12 Coen Hess, 13 Jason Taumalolo
Interchange: 14 Ben Hampton, 15 Shaun Fensom, 16 Corey Jensen, 17 Sam Hoare, 19 Ethan Lowe, 21 Francis Molo
Warriors: 1 Roger Tuivasa-Sheck, 18 Gerard Beale, 3 Peta Hiku, 4 Solomone Kata, 5 Ken Maumalo, 6 Blake Green, 7 Shaun Johnson, 8 James Gavet, 9 Issac Luke, 10 Agnatius Paasi, 11 Isaiah Papali'i, 12 Tohu Harris, 13 Adam Blair
Interchange: 14 Karl Lawton, 15 Chris Satae, 16 Bunty Afoa, 17 Simon Mannering, 20 Ligi Sao, 21 Anthony Gelling