The Reds not only turned the tables on the pre-tournament favourites, but they also outscored them by three tries to one - the latter from Wallaby wing Digby Ioane making the game safe and denying the Sharks anything from the game.
Springbok skipper John Smit started at tight head prop and the Sharks pack were expected to dominate at the set-pieces. But that never materialised as the highly charged home side set a fast pace and never allowed their visitors to settle into a game plan.
The Reds raced into a 15-0 lead, but were under pressure midway through the second half when a Ryan Kankowski try cut the gap to 18-13.
There was also bad news for another of the South African sides who are due to face the British & Irish Lions this summer. The Cheetahs were comprehensively beaten in Auckland by the Blues in the 1000th Super 12 and 14 match.
Their 46-12 defeat was their fifth in a row in the competition, leaving them rooted to the bottom.