The Sea Eagles, who were reduced to 12 men during the contest following the decision to send off Karl Lawton for a spear tackle on South Sydney lock Cameron Murray, will now be forced into three changes for next week's clash against a rejuvenated Wests Tigers outfit.
Parker has suffered a partially torn ACL ligament according to an official club statement and will spend at least four weeks in rehabilitation work for the knee before being reassessed.
Parker was taken from the field shortly after halftime during the loss to South Sydney, with the centre struggling to move freely on the troublesome knee.
Saab, on the other hand, played through the game and there had been no report of the winger being injured before Manly's Monday injury update, which revealed he had suffered a toe ligament injury during the contest.
While Lawton's suspension is easily replaceable with the return of Haumole Olakau'atu, who was suspended for the loss to South Sydney, the backline will present plenty of questions to be answered by Des Hasler.
Tom Trbojevic is an outside chance to return next week from an MCL injury, and if he does, Reuben Garrick will be shuffled onto the wing for Saab, with Christian Tuipulotu holding his spot on the other side of the park.
Morgan Harper is the most likely option to take Parker's centre spot, with Tolutau Koula also maintaining his spot in the side. Des Hasler was impressed by Ben Trbojevic off the bench however, and he could yet slot back into the centres.
Should Tom Trbojevic not be passed fit to play, then it could see a return for Jorge Taufua, who missed last week's NSW Cup clash with the Rabbitohs, but has otherwise been captainting the Sea Eagles feeder team - Blacktown Workers - from the centres.