Rhys Priestland steered Cardiff to a hard-fought 23-17 victory as his side survived a second-half onslaught from the Sharks.
The hosts led 17-0 at one stage but were hanging on grimly at the death and 13 points from the boot of the impressive Priestland proved just enough.
Cardiff’s tries came from Matthew Morgan and Willis Halaholo, with Priestland kicking two conversions and three penalties
Thomas Du Toit and Marnus Potgieter scored tries for the Sharks, while Curwin Bosch converted one and Boeta Chamberlain added a penalty and a conversion.
Cardiff began brightly to take a sixth-minute lead with a simple penalty from Priestland as the Sharks infringed four times in the opening eight minutes.
This ill-discipline proved costly as the hosts extended their advantage when Morgan danced past a couple of defenders for an excellent solo try which Priestland converted.
The Sharks should have then picked up their first points, but the normally reliable Ruan Pienaar was wide with a 30-metre angled kick.
The home side suffered an injury blow when Wales flanker Ellis Jenkins walked off to be replaced by Shane Lewis-Hughes.
The Sharks were gradually increasing their influence on the game but an excellent up-and-under and a chase from Jason Harries won his side a platform in the opposition 22, from where Halaholo carved a hole in the visitors’ defence to race away and score.
At 17-0 down, the Sharks needed a quick response and got one when Du Toit forced his way over from close range. Bosch kicked the conversion but was off-target with a long-range penalty attempt.
Chamberlain became the Sharks’ third kicker of the night and succeeded with a 30-metre kick to leave his side seven points adrift at the interval.
The third quarter was totally one-sided as Cardiff never got out of their own half, but their opponents lacked the guile to break down a whole-hearted defence and the quarter went scoreless.
Bosch attempted another long-range penalty but it sailed wide, as did a much easier kick from Priestland, although the former Bath outside-half made amends by knocking over his next attempt to give his side a 10-point advantage with 10 minutes remaining.
A converted try from Potgieter set up a tense finish, but a late penalty from Priestland sealed a morale-boosting victory.
