A New Zealand Rugby media release that states there will be a "major announcement" at the organisation's Wellington office at midday almost certainly refers to the pair, who are two of the best players in the world.
Lock Retallick was officially recognised by World Rugby as the top player last year, with wing Savea on the shortlist.
After a steady drip of players announcing they are about to leave for lucrative offshore deals, the signing of Retallick and Savea will be described tomorrow as a coup by New Zealand Rugby chief executive Steve Tew.