Olakau'atu was sent for scans on his injured calf by Sea Eagles officials on Monday afternoon, with results not due back until Tuesday.
The NSW State of Origin second-rower failed to finish Sunday's 32-22 loss to Penrith, but Manly officials were hopeful after the match the issue was not serious.
Olakau'atu debuted for NSW last week in their Game I loss, and Sunday's clash with St George Illawarra comes hours before the side for Origin II is named.
Manly could desperately do with Olakau'atu against the Dragons, having lost four of their past five to fall out of the top eight.
Hooker Lachlan Croker remains a week-by-week proposition, while fellow middle Matt Lodge is unavailable until round 24 with a bicep rupture.Â
Manly's Josh Aloiai has been slapped with a two-game ban for tripping in the loss to the Panthers. (James Gourley/AAP PHOTOS)
Aloiai is also at risk of joining him on the sideline, after being hit with the harshest sanction for a trip by the NRL in almost four years.
The prop was on Monday handed a grade-two dangerous contact charge, after replays showed him sticking his leg out and tripping the Penrith fullback on Sunday.
Laurie was not in possession of the ball at the time, and was only running in support after an Izack Tago break late in the Panthers' 32-22 win.
Aloiai can take a two-match ban with an early guilty plea, or risk extending the suspension to three matches if he challenges the charge unsuccessfully.
His absence will come as a blow to the Sea Eagles, with their next two matches crucial in keeping pace with the race for the top eight.
Aloiai is only the second player to face a ban for tripping in the past three seasons, with Isaiah Papali'i also suspended for one game earlier this year.
But Aloiai's bad judiciary record means he is facing a longer ban, and the harshest punishment for a trip since Jackson Ford in August 2020.
Fellow Manly prop Nathan Brown was also charged by the match review committee on Monday for a hair pull on Jarome Luai.
But he will be able to escape with an $1800 fine if he pleads guilty.
Elsewhere Melbourne second-rower Eliesa Katoa and Newcastle counterpart Kai Pearce-Paul were each charged from Sunday's matches, but can accept fines.
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