Trbojevic limped off at Suncorp Stadium in the 69th minute with what coach Anthony Seibold confirmed was another hamstring tweak for his star fullback, at least the fifth of his career so far.
Scans on Friday will reveal the extent of the injury, which will also have major ramifications for the Blues in their State of Origin campaign with Trbojevic slated to play centre in the series opener on June 5 in Sydney.
The 27-year-old tore Queensland apart in the 2021 Origin series at centre but missed all of the 2022 series after dislocating his shoulder. Last year he ruptured his pectoral in game two of Origin and missed the rest of the year.
In typical Trbojevic style, he suffered the latest setback while making an almighty effort to try to stop Dolphins winger Jack Bostock scoring in the corner.
That extra exertion appeared to be when his hamstring strain occurred, before he collided with a cameraman at speed.
Trbojevic was injured trying to stop a flying score from Dolphins winger Jack Bostock. (Dave Hunt/AAP PHOTOS)
The loss of Trbojevic for an extended period is bad enough for Manly but classy winger Jason Saab is also facing a lengthy absence after an AC joint injury while attempting to score a try in the 17th minute.
"Jason needs a scan but they are telling me it is a grade three," Seibold said.
"We have lost both of those guys for a period of time."
The Sea Eagles will welcome back barnstorming second-rower Haumole Olakau'atu from suspension against Brisbane in next Friday night's Magic Round blockbuster, also at Suncorp Stadium.
Hooker Lachlan Croker (concussion) and forward Nathan Brown (hip flexor) also missed the Dolphins clash but should be back next week.
"With Saaby and Turbo (Trbojevic) going down it does put a dint in our squad but there is a group there that really care about the footy team," Seibold said.
"We will put a team together next week and expect to come back here and put in a better performance for longer periods.
"We have shown we are a good footy side."
The Sea Eagles now go into camp on the Sunshine Coast to prepare for next week and extra troops are on the way.
"We are going to have to fly a few players up from Sydney," Seibold said.
The Sea Eagles have lost three games this year after taking healthy leads.
They were ahead 14-0 against Parramatta before losing 28-24. Last week they got out to a 20-0 lead over Canberra before suffering a 26-24 defeat at home. Against the Dolphins they were looking good at 16-4 when a five-minute lapse before halftime cost them three tries, and ultimately the match.
"We are in here talking about the same trend again so it is something we need to fix and something that all of us can help each other with," captain Daly Cherry-Evans said.
"We have got to change a few things to get the result we are after. We can fix it. We just have to work harder at it."
