The Manly Sea Eagles and New South Wales Blues have suffered a big blow, with veteran prop forward Jake Trbojevic ruled out for at least a month.

Trbojevic suffered a calf injury against the Gold Coast Titans during a Round 9 loss at 4 Pines Park on Saturday evening, and scans have revealed a Grade 2 injury.

That, according to the club, will leave him sidelined for at least four weeks where he will miss games against the Brisbane Broncos, Cronulla Sharks, Canberra Raiders and Newcastle Knights in a tricky stretch ahead for the club.

The opening game of the State of Origin series is only four weeks away, meaning Trbojevic will need his recovery to go perfectly to feature for the Blues, in a side he otherwise would have been a shoe-in for given his outstanding start to the year.

In eight games, he has played all but 19 minutes of the Sea Eagles' campaign, running for 103 metres per contest and tackling at a tick under 96 per cent.

He is joined on the sidelines for the Round 10 clash against the Broncos by Toafofoa Sipley, who is out suspended, meaning Taniela Paseka and Sean Keppie will start up front, with the bench featuring Karl Lawton, Ben Trbojevic, Ethan Bullemor and Aaron Woods, while Josh Aloiai remains at lock.

The other injury for Manly is to Morgan Harper, who will miss the game against Brisbane with adductor injury - it's only expected to rule him out for a single week, however, the returns of Tolutau Koula and Brad Parker leaves it unlikely the off-contract New Zealander will be selected in Round 11 against the Sharks.

Koula's return to action for Manly is joined by that of Brad Parker, Tom Trbojevic and Ben Trbojevic.

The brother of Jake, Tom missed last weekend with a hip complaint, but has passed all tests, while Koula is returning from knee surgery. Parker is in the same boat while Ben Trbojevic is back from a hamstring injury.

Manly's game against the Broncos will be played on Friday night in prime time at magic round.