Manly forward Jake Trbojevic.

Gun Sea Eagles forwards Jake Trbojevic and Addin Fonua-Blake will both sit out the entire off-season with shoulder surgery expected to rule them out of the opening rounds of 2020.

The Test duo are scheduled to go under the knife on Tuesday with a recovery period of up to four months predicted.

The recovery timeframe puts both Trbojevic and Fonua-Blake in severe doubt for Manly's season opener against Melbourne at Lottoland and their round two clash with the Roosters on the Central Coast.

It's understood both men pushed through the pain barrier in 2019 as Des Hasler's squad was repeatedly rocked by injury.

The cleanout surgeries for Trbojevic and Fonua-Blake continues that theme on the Northern Beaches. Tom Trbojevic (pectoral), Joel Thompson (arm), Curtis Sironen (foot) and Taniela Paseka (knee) all had their 2019 seasons ended by surgery.

That quartet will be eased back into pre-season training but are not in any doubt of missing Manly's March 15 showdown with the Storm, an expected Sunday afternoon sell-out at Lottoland.

Manly prop Addin Fonua-Blake.
Manly prop Addin Fonua-Blake. ©Gregg Porteous/NRL Photos

Hooker Manase Fainu is also recovering from shoulder surgery as he faces serious criminal charges that have led to him being stood down under the NRL's no-fault stand down policy.

Fainu is denying all charges after police allege he stabbed a man at a church dance in Sydney's south west.

Fainu was initially denied bail, with his next bail hearing set down for Monday, November 11.