A Simon Gillett wonder goal secured three priceless points for City and sucked visitors Gillingham back into the Sky Bet League One relegation scrap.
Sam Baldock opened the scoring in the first half with a fine strike of his own, only for half-time replacement Charlie Lee to draw the Gills level on 65 minutes.
It seemed set to peter out into an unsatisfactory share of the spoils until Gillett stepped up to drive home his first goal in two years to prompt a collective sigh of relief across BS3.
Steve Cotterill made five changes to his side beaten in what the manager described as an “abysmal” performance at Sheffield United last time out starting in goal, where Frank Fielding was reinstated for his first league start since September at the expense of Simon Moore, sidelined by a groin injury.
Elsewhere there was a first start in 11 months for Stephen Pearson in midfield, while Brendan Moloney, Gillett and Bobby Reid were all recalled.
Karleigh Osborne, Greg Cunningham, Marlon Pack and Tyrone Barnett all dropped to the bench alongside rookie goalkeeper Dave Richards.
It was an open start to the contest, with Gillingham causing a nervy moment with a low cross which City struggled to clear before Amine Linganzi’s shot was blocked at close quarters.
But from then on City grew in confidence. Gillett set his sights and let fly from 30 yards with a rising drive not too far away from its desired target, before Jay Emmanuel-Thomas threatened to run clear of the defence but ultimately hit a weak right-footed shot easily dealt with.
There was undeniably more intent about the Robins than throughout the 90 minutes at Bramall Lane.
Pearson led a menacing counter-attack, combining with Emmanuel-Thomas and Reid before the Scot played a low cross towards the far post which only eluded the striker’s outstretched leg by a matter of inches.
The visitors could have no complaints when City took a deserved lead on 27 minutes courtesy of a fine opening goal.
Some good work from Gillett set the wheels in motion, as the midfielder exchanged passes with Emmanuel-Thomas before finding Wade Elliott, whose floated pass was perfect for Baldock to wrongfoot his marker with his first touch and unleash a powerful half-volley across keeper Stuart Nelson from 16 yards with his second.
Having seen out the remainder of the first half with the utmost comfort, City set about increasing their advantage after the break, as Aden Flint climbed highest to meet Reid’s corner but could not quite keep his header low enough to trouble Nelson.
But Gillingham responded with their brightest moment of the game. Bradley Dack’s pass released top scorer Cody McDonald who forced a first notable save out of Fielding at his near post, before finding a cross back towards Dack who appeared to be hauled down by Moloney.
After City survived visiting appeals for a penalty, Adebayo Akinfenwa completed the ten-second frenzy with a shot towards the far corner which just did not curl enough to find the net.
It was a warning for the home side, who created their best opportunity to double the lead at the other end soon after, as Baldock played in Reid whose left-footed shot cleared the crossbar from a position of promise.
And City were made to pay as a painfully familiar set-piece goal spoiled their hopes of securing a rare clean sheet.
Substitute Myles Weston aimed the kick long, beyond the far post, for the sizable frame of Akinfenwa, whose header back across the box was dispatched in clinical fashion by Lee on the half-volley from ten yards.
Cotterill’s response was swift, introducing Pack and Wes Burns in a bid to turn the tide back in favour of his team.
But the Robins were struggling to create anything clear cut, and it would take a moment of individual brilliance from Gillett to swing the balance back in their favour.
Emmanuel-Thomas’ second long throw in quick succession was seemingly adequately cleared when the Nottingham Forest loanee picked up possession 30 yards from goal.
But having composed himself and weighed up his options, the midfielder rattled in an unstoppable shot which flew into the top corner to send Ashton Gate into a state of ecstasy.
It was a huge goal and potentially defining moment in the season, as City held on in the face of a late barrage to escape three points better off.