With the Sea Eagles in control of the game and up 34-12 , Trbojevic left the field carrying his right arm and with blood splattered across his face with 16 minutes left.
The Manly superstar appeared to have his right arm stretched when attempting to make a tackle on Jacob Preston, before teammate Luke Brooks landed on it.
Trbojevic looked devastated as he left the Accor Stadium field, having had a woefully unlucky run of injuries, and having even asked for a pay cut earlier this year as a result.
But Manly were confident after the match the 27-year-old had only suffered an AC-joint injury, with club officials saying he would be fine to play in the finals with a pain-killing injection.
Manly dominated against Canterbury, showing they could be a strong threat in the finals. (Dan Himbrechts/AAP PHOTOS)
"He will be right for week one of the finals. There is something there that can take the pain away," coach Anthony Seibold said of Trbojevic.
"He will definitely miss next week from what I understand. He will get an x-ray or scan.
"We'll put a plan together for him and make sure we look after him.
"The good thing is those injuries aren't season ending. There is some pain there, and he will be a bit sore and sorry for the next few weeks.
"But he will be right to go for week one."
Making matters worse for the Sea Eagles, winger Jason Saab suffered a syndesmosis injury early in the match after a Bronson Xerri hip-drop tackle. Xerri was put on report.
He will require scans, but there are fears the injury could sideline him for some time.
Lehi Hopoate was a key contributor for Manly with a try in each half. (Dan Himbrechts/AAP PHOTOS)
The injuries ruined an otherwise perfect night for Manly, who made another real statement against one of the competition's in-form teams.
In front of a record crowd for a 6pm game outside of Magic Round of 35,502, Manly piled on the most points of any team against the Bulldogs this year.
Luke Brooks was superb just two weeks out from his long-awaited first finals series, but had a minor scare after being put on report for a dangerous throw.
The five-eighth set up one try when he toed ahead a Haumole Olakau'atu offload, regathered and put Trbojevic away on his inside to score.
Another first half try came when he looked out the back and went short to Karl Lawton, allowing the second-rower to go under virtually untouched.
And when Manly led 24-12 at the break, it was a one-on-one strip from Brooks that put the Sea Eagles back on the attack for Lehi Hopoate to cross.
Reuben Garrick iced the win with Manly's sixth try. (Dan Himbrechts/AAP PHOTOS)
Taniela Paseka and Matt Lodge were immense for Manly in the middle, while Olakau'atu was damaging in defence and attack in the second row.
Hopoate was also influential, scoring a double and both times making use of limited space to get to the line.
In comparison, this was the Bulldogs' worst game in months.
They were able to stretch Manly down the right edge multiple times, but two errors on attack before halftime and an obstruction after the break proved costly.
Matt Burton also finished the game with a concussion, meaning he would require an exemption to play North Queensland next Saturday night at Accor Stadium.
"That's the first time this year I have walked off really disappointed in our defence," Bulldogs coach Cameron Ciraldo said.
"We let in six tries. I really didn't like that. The way we let them in was really poor."
Friday night's result means Canterbury's top-four hopes are all but shot, and they must beat the Cowboys to wrap up a home final.
The loser of that match will be at risk of slipping to seventh and behind Manly, if the Sea Eagles beat the Sharks at Brookvale next Sunday.
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