Hopoate will start the match in the second row with Sam Harris to add some grunt up front against the massive Warriors pack.
Hoppa's promotion means a return to the centres for skipper Steve Menzies who will partner Albert Torrens.
King hasn't played this season and has made a good recovery from an off season shoulder operation.
His return is timely because he adds size and power up front against the yet to win but talented Warriors outfit.
The Manly Sea Eagles NRL side is:
Andrew Walker,Scott Donald,Albert Torrens,Steve Menzies (c),Chris Hicks,Jye Mullane,Michael Monaghan,Daniel Heckenberg,Chad Randall,Ian Donnelly,Sam Harris,John Hopoate,Luke Williamson.Replacements: Jason King,Kane Cleal,Anthony Watmough,Shane Dunley.