Depleted Cardiff delivered a brave display as they came away with a four-try bonus point from a chaotically entertaining encounter at a packed Arms Park.
There were two touchdowns from teenager Tom Bowen, who had a tremendous game, with fellow winger Gabriel Hamer-Webb and flanker Alex Mann also crossing.
With seven minutes to go, there was just one score in it and the home fans in a 11,687 crowd were sensing the possibility of a famous victory.
But the Sharks claimed two late tries to finish with six in all and deny Cardiff a second bonus point, which sees the South Africans nip above them into fourth place in the URC table.
However, Matt Sherratt’s team can take a lot of heart from how much they contributed to the contest given their reduced ranks.
They were without all eight of their Wales Six Nations squad members – Josh Adams, Taulupe Faletau, Ben Thomas, James Botham Keiron Assiratti, Teddy Williams, Ellis Bevan and Evan Lloyd – along with around a dozen players through injury.
With Bevan away on international duty and Aled Davies sidelined with a shoulder issue, there was a first start for South African Johan Mulder against his countryman, while Ethan Lloyd came on for his regional debut after stepping up from the semi-pro club side.
Second row Josh McInally took on the captaincy for the first time, with Callum Sheedy returning at No 10 and Regan Grace making his Arms Park bow off the bench.
As for the visitors from Durban, they had no fewer than 13 Springboks in their match-day 23, including World Cup winners Makazole Mapimpi, Bongi Mbonambi, Vincent Koch, Lukhanyo Am, Grant Williams, Trevor Nyakane and Jaden Hendrikse, whose brother Jordan started at full-back.
It was the annual clubs’ day at the Arms Park with more than 1,500 youngsters from some 30 different clubs in the region in attendance and adding to the atmosphere.
When the game got underway in good playing conditions, it was the hosts who made a dream start with a sparkling try after just seven minutes.
After Jordan Hendrikse failed to deal with a Sheedy bomb, Hamer-Webb pocketed the deflection and made good ground down the right with second row Seb Davies adding further ground.
Then when the ball was moved right, centre Rory Jennings put in a pinpoint cross-kick which Wales U20s squad member Bowen took on the run before stepping inside twice to beat three defenders.
The young winger was eventually brought down five metres from the line, but quick recycling saw the ball spun left where Rey Lee-Lo spun away from a defender and fed McInally who unselfishly gave the scoring pass to blindside Mann.
Stung into action, the Sharks responded with a period of sustained pressure which culminated in two tries in the space of four minutes.
First hooker Mbonambi stormed over after breaking off a lineout drive and then centre Julius Jurenzo followed him in crossing the whitewash as the defence was breached.
Cardiff came tantalisingly close to hitting back midway though the half as prop Rhys Barratt charged through only to be brought down inches short and then penalised for a double movement as he tried to squirm the ball past the whitewash.
It was then the Sharks’ turn to be denied a try, with a TMO review deciding that prop Ntuthuko Mchunu had been held up over the line.
But they weren’t to be kept out for long.
A hoisted cross kick from fly-half Siya Masuku saw the ball evade Cam Winnett and bounce up for wing Mapimpi to cross, with Jordan Hendrikse adding a third conversion.
Yet it was Cardiff who had the final word in the half with an even better try than their first one.
They went through some 15 phases, probing down both flanks, with Seb Davies surging up the right touchline, Rhys Litterick carrying strongly and Thomas Young showing great feet in midfield before the ball was moved left.
Then it was over to the speedy Bowen who looped around McInally, eluded the clutches of one defender and scrambled back up after being ankle tapped by another to get the ball down in the corner. It really was a fine team try and a fine finish.
Leading 21-10 at the break, the Sharks immediately stretched their lead once again when Mchunu burst through and gave an offload to front row pal Mbonambi who powered over for his second.
But Cardiff swiftly bounced back with Bowen completing his own brace.
This time he profited from an intelligent grubber kick from Winnett, taking the ball on the bounce and cutting inside the last man to gleefully slide over underneath the posts.
The Sheedy conversion cut the deficit to 28-17 and, after Bowen had threatened a hat-trick with a kick and chase, the gap was cut still further when Hamer-Webb went over for a fourth bonus point try just before the hour mark.
It was another really well worked score.
Off a lineout on the opposition 22, Lee-Lo and the ubiquitous Bowen both hit good lines to test the defence and then after a series of forward carries the ball was shipped left through the backs with Winnett sending out the long lofted scoring pass to his wing.
At the stage, Cardiff were right back in the hunt and sniffing a dramatic victory, while even defeat would mean two bonus points if the score stayed the same.
But, in the closing stages, Francois Venter and Yaw Penxe both went over to seal the win for the Sharks and reduce the home side’s haul to one point, via their four tries.