Manly's finals campaign could be dealt another major blow after prop Martin Taupau was reported for a high shot in Friday's 32-16 NRL loss to Parramatta.
Taupau was sin-binned after his second-half swinging arm whacked Eels forward Ray Stone across the jaw and forced him from the field in a medicab.
Having already lost star fullback Tom Trbojevic to a season-ending pectoral injury, the Sea Eagles could now be without Taupau for next week's elimination final.
Further souring the defeat was a knee injury to rookie forward Taniela Paseka, while second-rower Curtis Sironen also failed to finish the match a leg issue.
The 16-point win means Parramatta finish fifth and the Sea Eagles sixth, however their week-one opponents will be decided on Saturday and Sunday.
Manly will face Brisbane should the Broncos defeat Canterbury on Saturday, while the Eels will meet either Cronulla or the Wests Tigers at Bankwest Stadium.
Eels front-rower Kane Evans was also binned and cited after his shoulder made contact with Sea Eagles centre Brad Parker later in the match.
Replays later showed Evans' shoulder bounced up off Parker's arm and into his head, however it was enough to send him for a concussion test.
The Taupau shot drew fierce criticism from the commentators.
"If they don't think that's a send off... there's no other high tackle you can do that's worse than that," said Fox Sports commentator Braith Anasta.
Sea Eagles coach Des Hasler admitted to being concerned about the incident.
"I'll have to check Martin Taupau's carryovers. I'm a little bit worried about that one. Both players (Martin and Kane) will be a little bit worried about it," he said.
Led by a hat-trick from breakout star Maika Sivo, the Eels were the better side for most of the match and were leading by 16 points when Taupau was marched.
The Sea Eagles showed plenty of courage to stay in the contest with two tries to back-up hooker Manase Fainu to be within eight with 20 minutes to go.
Manly got to within six on a 65th-minute penalty goal, however Sivo sealed the victory with two tries in the final eight minutes.
The crowd of 25,034 chanted Sivo's name after both four-pointers.
His three tries takes him to the top of the try-scoring charts with 20, three ahead of Warriors winger Ken Maumalo, who plays on Saturday.
Eels coach Brad Arthur said Sivo had bounced back after a couple of quiet weeks.
"If he carries hard out of the backfield early, it sets him up and he'll find a way or we'll find a way to get him the ball and he's pretty hard to handle," Arthur said.
The Eels flew out of the blocks with two tries in the space of three minutes to Michael Jennings and Clint Gutherson.
Jennings' fifth minute opener came off a devastating Sivo run, before Waqa Blake got in the clear for Gutherson in the next set.
Their lead blew out to 14 after a Mitchell Moses penalty goal before Manly stabilised with two try-saving plays to be down by 12 at the break.
But the Sea Eagles were left to rue two golden chances either side of halftime, with Jorge Taufua and Reuben Garrick bombing certain tries.