"He has been letting us know he's been ready for the last two or three weeks but we are just making sure he's ready to come back [from his groin injury].
"He'll be having some time in the dummy half role against Brisbane and he'll also give us cover in the halves.
"Bringing Agnatius in for his debut is really exciting for us. He's been impressive for our New South Wales Cup side and has worked hard for this opportunity.
"It's tough on Charlie [Gubb] and Sam [Lousi] but Agnatius deserves to have his chance in first grade."
Saturday night's clash will be Leuluai's 29th game in his second stint with the Warriors after he played 21 times in 2003 and 2004 before spending the next eight seasons in the English Super League.
The seasoned Kiwi international was on the field for every minute of the Warriors' 24 matches last year - a total of 1920 minutes - before a groin complaint ruined his World Cup campaign.
Leuluai returned for the fourth-round victory over Wests Tigers in April.
He also appeared in the next three matches before being sidelined again.
Mangere East junior Paasi, another St Paul's College product, was in the club's NYC premiership-winning side in 2011, going on to play New South Wales Cup football for the now-defunct Auckland Vulcans.
He was signed on an NSW Cup contract with the Warriors this season.
Paasi and Leuluai join Ben Matulino and Feleti Mateo on the bench while second rower Jayson Bukuya, who missed the Parramatta match, is the fifth player named on the interchange.
The Warriors beat Brisbane 19-10 at Mt Smart Stadium on June 21.
They were four points behind the Broncos on the ladder going into that contest but with that victory, subsequent wins against Penrith and Parramatta plus a bye they have collected eight points to move to sixth spot on 22 points.
Brisbane are just two points behind in seventh place.
