Down 26-0 midway through the second half, the Roosters put on a brief comeback late in the second half with the majority of their big names back on the field.
But it wasn't enough to overcome an impressive Manly outfit, who all but wrapped up the inaugural pre-season challenge with the win.
The real concern, though, was off the field for the Roosters.
Suaalii was hurt when he got his head in the wrong spot trying to take down Sea Eagles wrecking-ball Haumole Olakau'atu.
The teenage superstar was sent from the field for an HIA and did not return.
Little more than two weeks out from their season opener against the Dolphins, Suaalii joins fellow centre Joey Manu (jaw) in racing the clock to play at Suncorp Stadium.
Luke Keary (jaw) and Jared Waerea-Hargreaves (back) have also suffered injuries but are hoping to be fit, while second-rower Angus Crichton has taken personal leave.
Connor Watson also suffered a knee injury last month that will rule him out of for the opening months, while Sitili Tupouniua (knee) remains sidelined.
Without Sam Walker due to COVID-19, the Roosters were poor in attack as they completed at 63 per cent.
Manly on the other hand looked slick without three-quarters of their spine in Tom Trbojevic, Daly Cherry-Evans and Lachlan Croker.
Young hooker Gordon Chan Kum Tong was particularly impressive, regularly darting out of dummy-half as he had a hand in two tries.
He signed a new deal to join Manly's top 30 next season, and while he is listed as a development player this year he looks every chance to debut at some point.
Reuben Garrick also bagged two tries on the left wing, with the Sea Eagles' fluent down that side as Josh Schuster playing his first game as full-time five-eighth.
Manly's win leaves them atop the pre-season challenge, one offload short in the win from claiming enough bonus points to wrap up the title and $100,000 prize but still in the box seat.
Only the Warriors, Canterbury or Cronulla could topple the Sea Eagles, if they win, claim all bonus points in their matches this weekend and better Manly's for-and-against.
But there were some minor concerns for Manly, with Morgan Harper limping from the field late with a knee injury and fellow centre Brad Parker receiving two blows to the nose.
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