Warriors prop Ben Matulino expects Manly to come out firing after a tough week on and off the field.
The Sea Eagles go into the NRL clash in Auckland on Saturday in danger of missing the play-offs for the first time in 11 seasons.
"They're in the position where they pretty much need to win all their games to make the final eight," Matulino said.
"They know where they need to be. They'll come out firing and we can't just turn up and expect to win."
Both Manly and the Warriors will head to Mt Smart Stadium backing up from defeats.
The Sea Eagles' 30-12 loss to North Queensland halted a brief upswing in fortunes and left them in 13th spot, six points out of the top eight.
It was followed by a report that 14 players have been told they are not wanted next season.
The Warriors went down to the Sydney Roosters 24-0 to end a three-match winning streak and drop from fourth to seventh on a congested table.
Poor ball security proved costly against the Roosters, the Warriors completing just three of their first 10 sets, although they improved to 67 per cent by the end of the match.
"That's the big one," Matulino said.
"We didn't get too many chances at attacking in their end. You can't expect to win out of your own half and I guess that's how we played."
Against Manly, the Warriors will again be without three frontline players in winger Manu Vatuvei, centre Konrad Hurrell and second rower Ryan Hoffman.
Vatuvei and Hoffman are still recovering from respective shoulder and back problems.
Hurrell is sitting out a one-match ban for dangerous contact while playing for the Warriors' NSW Cup side in his come-back from a shoulder injury.
Manly's line-up includes star half-back Daly Cherry-Evans, who came off against the Cowboys with a shoulder issue.
Matulino, who has been on a winning Warriors side against the Sea Eagles only once in eight seasons of first grade, has no doubts about Cherry-Evans' influence.
"Every time I play Manly, he's a big part of them," he said.
"He's always running the show."
Matulino will come up against a familiar face among the opposition forwards in former Warriors teammate Feleti Mateo.
"I'm looking forward to catching up with him, but not playing against him," Matulino said.
"He's just hard to defend. He pops offloads and all that. He gets under your skin, the way he plays."