The loss of Johnson in particular is a huge blow to the side's attacking hopes, with the 27-year-old enjoying a purple patch of form across the Warriors three season opening wins over the Rabbitohs, Titans and Raiders.
The absence of Gavet means the Warriors will be further down on forward power and without two of the front-rowers that have featured in the past three games, with Sam Lisone serving a one-match ban.
A post on the club's website says Gavet's replacement is still to be confirmed while bench forward Bunty Afoa is listed in his place among the the starting side in the NRL's updated team lists.
Along with Gavet, wing Charnze Nicoll-Klokstad was the other player cut from the extended 21-man squad last night, with coach Stephen Kearney due to confirm his final 17 an hour before kick-off.
The onus will be on new recruits Adam Blair and Tohu Harris to lead the way for the visitor's forwards, along with hooker Issac Luke, while new five-eighth Blake Green's experience will be vital in steering the side around the park.
The understrength Warriors go into tonight's match looking to continue their unbeaten start to the season following wins over the Rabbitohs, Titans, and Raiders.
Last week's dramatic 20-19 last-minute win over Canberra was the first time in the club's 24-year history that they have won their opening three matches, and they will hope to continue to break new ground with a fourth-straight victory over one of the premiership favourites.