The Mount Smart club held a surprise 18-nil lead at half-time, before a 67th minute Adam Blair sin-binning saw Manly run in three unanswered tries in just seven minutes.
However, a late Jazz Tevaga try saw the Warriors break a six game losing run at home.
Coach Stephen Kearney says they found a way to win and that's all they wanted.
Penrith's held off Cronulla 26-20.
RUGBY LEAGUE COVERAGE POWERED BY MACHINERY HOUSE - IN A LEAGUE OF THEIR OWN