Sale director of rugby Philippe Saint-Andre used the match as an opportunity to rest his established players amid a gruelling schedule, which saw his side play at London Irish on Wednesday and lose their unbeaten start to the season.
A 28-6 reverse at the Madejski Stadium ended the Sharks' run of four straight victories in which they did not concede a try to set a new Premiership record.
Not one of the players who lined up against the Exiles were retained in a youthful-looking starting line-up against Cardiff as Saint-Andre fielded a team of fringe players.
Seven of Sale's starting XV were given their first taste of first-team action this season, among them former Cardiff utility-back Nick Macleod, who lined up to make his debut at full-back against his former club.
That Macleod struck the opening blow with a well-struck penalty from 40 metres to edge Sale ahead in only the second minute looked a promising omen for Sale.
Ben Blair, Macleod's opposite number, then spurned the chance to draw Cardiff level moments later when he skewed a penalty wide, but Macleod did likewise in the 10th minute as both sides initially struggled to find any rhythm.
That changed in spectacular fashion in the 12th minute when Cardiff cut Sale to pieces thanks to a piece of individual skill from scrum-half Richie Rees.
Rees, collecting possession on the right-hand side of the pitch around 40 metres from the visitors' line, advanced forward at pace and sold two Sale players a delightful dummy, giving him the space to sprint forward and send the supporting Halfpenny over the line with a clever underarm offload.
Halfpenny gave his side the best possible chance of the additional two points by touching down under the posts, and Blair duly obliged with the boot to put the Blues 7-3 ahead.
Sale needed only three minutes to find a score of equal quality as stand-in scrum-half Chris Leck's long offload found Spaniard Oriol Ripol lurking on the left flank.
He raced forward and played a neat one-two with Richard Wigglesworth before a neat, short offload sent Keil over the line from close range.
Macleod failed to convert and then both and he Blair missed penalties as the blustery conditions made kicking duties difficult.
Both men did, however, claim penalties before the interval to ensure Sale went in at the break with a slender 11-10 advantage, but they were a man down for a short period either side of the break after Marc Jones was sent to the sin-bin.
Another Macleod penalty edged Sale further ahead after the break but Ceri Sweeney added a penalty for Cardiff to keep the gap to one point.
Macleod's fourth kick looked to have sealed it for the hosts but it was Cardiff who clinched the win when Mustoe finished off a fine, flowing move in the left-hand corner.