Gagai, who re-joined the club from South Sydney last year, featured in Newcastle's final trial match against Parramatta last week, however the 32-year-old failed to come through the match unscathed.
The Newcastle Herald is reporting that the centre tweaked his hamstring in the clash, his first match since the Knights' final round loss to Cronulla last year, and remains under an injury cloud for the trip to New Zealand.
While the injury isn't considered a major one, it's enough to potentially keep Gagai grounded for the opening round, and open the door for a young gun at the club.
It's expected Gagai will still be named for the clash against the Warriors, however is no certainty to take his place in the side.
Hymel Hunt and Enari Tuala also shape as options if the Maroons' veteran does fail to face the Kiwi club, though the latter missed both trials with a pec injury, and remains under an injury cloud of his own.
Whoever does feature at right centre will line-up inside Dominic Young, with Newcastle fans calling for the winger to be dropped to NSW Cup in favour of Mapapalangi, or traded to the Roosters in return for a star effective immediately.