The Sharks finished with 13-men after Maybank’s patience finally snapped and he sin-binned England’s forwards Chris Jones and Andrew Sheridan for technical offences.
Gloucester laid siege to the Sharks’ line, desperate to make their two-man advantage count, and Maybank proved their matchwinner by making his 90th-minute decision.
Sale players were serious at the final whistle, but Gloucester’s perseverance in monsoon conditions ultimately reaped its reward.
Sale looked to have done enough thanks to first-half tries from England wing Mark Cueto and their French number eight Sebastien Chabal.
But they were not to know that Maybank would allow such a prolonged period of injury-time and Gloucester’s shear physical power eventually took its toll.
Gloucester though, did not emerge unscathed from the encounter, with their England centre Mike Tindall limping off injured 50 minutes into his home league debut and Tindall’s World Cup-winning colleague Phil Vickery receiving a yellow card midway through the first half.
Sale arrived in the west country hoping to underline their title credentials.
And Cueto equalled the league try-scoring record by touching down for a sixth successive game.
Cueto, according to the Rugby Union’s take on an 11-week rest period for English Lions, should not have played more than 40 minutes.
But Sharks boss Philippe Saint-Andre again defied Twickenham top brass by fielding Cueto and his fellow Lions Jason Robinson, Charlie Hodgson and Sheridan.
The collective outcome was a determined, organised effort from Sale and they looked to establish themselves as early Premiership pacesetters, but Gloucester had other ideas.
The appalling weather caused road closures near the ground and powercuts at various points inside Kingsholm, and it was no surprise goalkickers from both sides endured a frustrating afternoon.
The normally prestigious Ludovic Mercier landed just four from eight attempts, while opposite number Hodgson missed three kicks and full-back Daniel Larrechea booted two penalties out of four.
Both sides inevitably and repeatedly spilled some prime possessions, such were the conditions, yet Gloucester will be delighted to have prevailed as their new coaching team of Dean Ryan and Bryan Redpath settle in.
Gloucester were looking for a big contribution from Tindall, and there were times when he looked the part after such a prolonged injury absence.
His early departure did not appear to be the result of a serious injury, but Gloucester clearly need him fit and firing on all cylinders.
Cueto’s 35th minute try ensured a 12-6 interval lead for Sale, but Gloucester narrowed the deficit to one point just after half-time when hooker Olivier Azam powered over from close range.
A penalty double from Larrechea kept Sale clear, until the dramatic injury time finally which saw Maybank brandish two yellow cards and the Sale pack finally finding themselves outmuscled.