"There was a chance that he wasn't going to need a surgical procedure, but the surgeon in both New Zealand and Australia has decided that would be the best way forward," Morgan said.
"He will have surgery later this week, so that means he's likely to be missing for the remainder of the season; it's a 10-to-12-week rehab process with the surgery.
"It's not great news for Chanel, but at least there's some definitive answers around how to rehab it and when he does come back, fingers crossed he'll be 100 per cent able to do everything that is required and not make it more prone to a re-injury, which would be devastating for him."
It's a big blow for the 22-year-old, who missed six rounds of football earlier in the NRL season due to a broken foot.
After being given chances in first grade over the past couple of seasons, many hoped to see Harris-Tavita come into his own as a NRL playmaker in 2021 as he stepped into the role full time. However, it appears his season will be limited to seven games, with Sean O'Sullivan expected to deputise in his absence.
O'Sullivan has been named to start alongside Kodi Nikorima in the halves for Saturday's match against the Newcastle Knights despite the return of young star Reece Walsh, who comes back into fullback following a one-match suspension, with Roger Tuivasa-Sheck pushing out on to the wing.
Morgan said while Walsh has shown his ability as a playmaker in his short NRL career and would have a roaming role in the offence, there was one big part of his game that was not suited to a permanent role in the front line.
"I'm not sure if you remember him defending in the front line against Manly back at Lottoland or Brookvale or 4 Pines stadium or whatever it's called these days," Morgan said.
"He needs to nail down one position defensively, and I know (head coach Nathan Brown) has been working really hard with him on his positional play at fullback. We feel that rather than chopping and changing him and getting him to defend at three-man, getting him to defend at two-man, let's lock down the role at fullback, because that's where he's going to be for us long term. And it also takes a bit of stress off his body with big boys running at him if he was in the front line.
"So, while offensively it does make sense for him to play in that role, we feel it would be too taxing on him physically to defend in the front line at the moment, and in terms of his education – he's still learning about that game."
Hooker Wayde Egan is also a doubt for the next few weeks after suffering a head clash late in the match over the weekend, where he was rushed to hospital post-game with a serious concussion.