Manenti cracked 88 as South Australia were bowled out for 272 just before stumps on day one at the Gabba.
Easily the Shield's fastest scoring side, the Redbacks scored their runs off 80 overs after a rain-hit afternoon.
New Redbacks' captain Jake Lehmann was the other main contributor with his quickfire 65 coming off just 58 balls.
But the burly Manenti was the star with 15 boundaries in his 101-ball knock.
It was a third half-century in four innings for the No.8 who is fast making a case to be considered an allrounder.
South Australia looked in deep trouble with Lehmann's dismissal leaving the visitors at 6-111 after being sent in to bat by the Bulls.
Wicketkeeper Harry Nielsen also made an important contribution down the order before being dismissed late in the day for 47.
Michael Neser (3-60) and Xavier Bartlett (3-45) were the chief wicket-takers for Queensland.
The latter dismissed Manenti after a flashing drive was caught in the gully.
South Australia lined up without Wes Agar, the Shield's leading bowler, who is being rested ahead of next Wednesday's One-Day Cup final against Western Australia.
The second-placed Queensland went into the penultimate round fixture sharing second with the in-form Victoria.
