Maynard has found himself on Sven-Goran Eriksson's shopping list all summer, with the Robins rejecting three bids for the 24-year-old, and he will have irked Eriksson and the Foxes further with a strike in either half to ensure defeat followed hot on the heels of Saturday's reverse to Reading.
His first was a sumptuous free-kick from 20 yards in the opening five minutes, and although he missed a penalty on the stroke of half-time, he capitalised on a calamitous error from Sean St Ledger to ensure the points were won for the first time this campaign.
It was a poor showing from Leicester, who, barring a 20-minute surge of pressure where David Nugent equalised with an effort from distance, offered little to suggest they are worthy of pre-season opinions predicting them to run away with the division.
Maynard's performance may well encourage the Foxes to dig deeper into their pockets to bring him to the East Midlands, while Bristol City will be hoping to fend off further interest in the wake of tonight's showing.
Both sides made changes with Robins boss Keith Millen denying goalkeeper David James the opportunity to face former England manager Eriksson, who gave him 32 caps, by demoting the veteran to the bench.
Before the game Eriksson had urged his players to show the "real Leicester City", but the visitors had clearly not read the script, as they surged into a fifth-minute lead.
And the source would have proved a further frustration for the Swede as Maynard, subject to summer-long interest from the Foxes, lashed in a 20-yard free-kick that Kasper Schmeichel had no chance with.
It was neither the start or then the response the home side would have wanted and they nearly slipped further behind in the 25th minute, but Albert Adomah's low drive across goal was deflected perilously past the post.
And Leicester had an even bigger reprieve in first-half added time as after Gelson Fernandes had bundled over Jamal Campbell-Ryce, Maynard crashed the resulting penalty into the woodwork and the danger was cleared.
Leicester came back out with a renewed purpose and could have levelled within three minutes of the restart but Dean Gerken did superbly well to claw away Andy King's header.
The pressure continued and the home side were rewarded with an equaliser in the 55th minute.
After misplacing a pass, Paul Gallagher won the ball back for the Foxes, prodding to Nugent and the former Portsmouth striker fired in his first goal for the club with a 25-yard strike that went through the hands of Gerken and into the bottom corner.
And they should have been ahead with their next attack but Gallagher criminally dragged his effort wide.
Leicester were firmly in the ascendancy but they shot themselves in the foot midway through the second period when St Ledger was caught dawdling in possession and Maynard raced clear and restored Bristol City's lead with an assured finish from the edge of the area.
Typical of their performance for the majority of the game, Leicester had little in the way of a response and it was the visitors that nearly scored again but Kalifa Cisse blazed horribly wide.