News Corp reported on Monday afternoon that Tupouniua, who spent the first half of the season recovering from an ACL injury, was now suffering from a bulging disc in the neck, with no chance of a return this season.
The Roosters revealed he had complained of nerve pain on Saturday evening and had sustained an acute disc injury. The club have put no return timeline on the second-rower, though, instead saying he will meet with a spinal injury consultant before proceeding.
The Roosters also lost all of Angus Crichton, Egan Butcher and Jake Turpin during Sunday's clash with the Canberra Raiders, with Crichton's injury likely to see the second-rower sidelined for a lengthy period.
The club have confirmed he has suffered a moderate-grade medial collateral ligament injury, and while rehabilitation will commence in the coming days, he will spend some weeks out of the game - the club again have given no timeline.
Egan Butcher will be out for 11 days after suffering a HIA, while scans have confirmed Turpin of a serious rib injury, although it's not known how soon he might be back on the field.
In better news for the Roosters, Brandon Smith's recovery is making strides, with the hooker targeting a Round 20 return, while Sam Walker has resumed full team training and could be a chance of returning in the next fortnight.
Nat Butcher is also not out of contention to play during Round 1 after suffering an ankle injury at training last week.
All of Paul Momirovski, Connor Watson and Tyler Moriarty are also continuing their rehabilitation work from injury. It's believed Watson - a key figure for the Roosters - could be available in the coming weeks.
The Roosters, who have won just 7 from 15 games this season and sit in 12th place on the table, must find a way to turn things around this weekend when they clash with the Manly Sea Eagles before heading into their final bye of the season ahead of Origin 3.