Manly medical staff were on Wednesday hopeful Navale could return late in the year, but still his 2026 season is in tatters after injuring his right knee.
Navale played seven games for the Sea Eagles last season, and the Fijian international had loomed as a genuine option in the middle this year.
"We're all feeling for Caleb at the moment," Manly coach Anthony Seibold said.
"He's had his best pre-season ever and was on track to be a regular in our match-day line-up.
"I do know Caleb will throw everything he can into his rehab, and the goal now is to get him back before the end of the season."
The Sea Eagles possess one of the fastest backlines in the NRL, but their biggest issue for a long time has been a lack of forward depth.
Manly have recruited Brisbane's Kobe Hetherington for this season, but have lost middle forwards Toff Sipley, Josh Aloiai, Jazz Tevaga and Matt Lodge from their roster.
Veteran lock Jake Trbojevic is also attempting to make his return from repeated concussions, after having his season ended early last year by a series of head knocks.Â
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