The Sea Eagles were on Saturday counting the costs of their Friday night horror show, with Trbojevic and Daly Cherry-Evans both injured in the loss to the Warriors.
After initially believing scans may not be necessary, Manly have now opted to book Trbojevic in for assessment on Sunday morning.
The club is insistent the scans are only a precaution and that Trbojevic had only suffered tightness when he left the Go Media Stadium field with 15 minutes to play.
Unlike Trbojevic's six previous hamstring injuries, the fullback did not pull up while running or show any clear signs of immense pain when he felt the tightness.
Manly will also monitor Cherry-Evans' back, after he too left the field while struggling with back spasms late in the loss.
Any absence of either of the pair would come as a serious blow to the Sea Eagles.
While Lehi Hopoate has proven a reliable back up in the No.1 jersey in the past year, the Sea Eagles are clearly a better side with Trbojevic on the field.
Manly have won 37 of 57 games when Trbojevic has started at fullback since the beginning of his 2021 Dally M year, scoring 58 tries and setting up 61 in that time.
Their record without him during the same period is 15 wins from 46 matches.
Cherry-Evans has previously had a charmed run with injuries, the halfback having barely missed a game outside of representative duties in recent years.
The 36-year-old collapsed to his knees while standing at marker late in Manly's loss, before clutching for his lower back.
Their injuries came on a busy night for the NRL's biggest-name players, as Penrith also wait on the result of scans on Dylan Edwards' groin.
The Panthers were hopeful the Kangaroos Test fullback's injury was not a bad one, given the fullback was able to move around well on Saturday morning.
The injuries weren't the only issues for the NRL out of Friday night.
Manly's back-up hooker Gordon Chan Kum Tong has found himself at the centre of an NRL investigation, after he approached two Warriors fans late in the match.
A video circulating on social media appeared to show Chan Kum Tong grab a fan's jersey as he ran past the player's area, before another supporter intervened.
"The NRL is aware of the video shared on social media and is making enquiries," an NRL spokesman said.
The Sea Eagles' starting hooker Jazz Tevaga is also facing a $1800 fine out of the match, for a contrary conduct charge.
AAP understands the former Warriors utility is accused of throwing two water bottles at Demitric Vaimauga while the hosts celebrated their last try.
Tevaga was on the field at the time and there is no risk of a suspension.
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