Blues were easily second best in the first half to trail 19-7 but four second-half tries kept them in play-off contention – though they remain eight points behind third-placed Scarlets.
After a scrappy opening 10 minutes, Benetton took the lead with an excellent try. Melbourne-born wing Monty Ioane tore the home defence to ribbons to provide skipper Keatley with an easy run-in.
Keatley’s conversion rebounded back off a post before Blues produced their only threatening attack of the first quarter. Forwards Olly Robinson and Liam Belcher made strong bursts into the heart of the Italian defence but inaccurate handling from Blues saw the move break down.
After 21 minutes, Treviso scored a second try after Keatley’s kick had secured a line-out in the opposition 22. From there, the visitors’ pack rumbled forwards for lock Herbst to score.
Keatley converted before Blues responded with a period of pressure, which culminated in Harries outflanking the cover defence to score.
Tovey converted with a splendid touchline kick before Keatley missed a straightforward penalty, with his kick again coming back off a post.
Blues received an injury blow when prop Rhys Gill was led off with a shoulder problem before they suffered another setback when powerful Benetton number eight Halafihi crashed over from close range.
Keatley converted to give his side a well-deserved 19-7 half-time lead before Blues showed some urgency to reduce the arrears when Smith ran strongly to score.
Cardiff were now rejuvenated and aided by a yellow card for Keatley for a deliberate knock-on, they drew level.
A clever crossfield kick from Tovey was collected by Edwards to score before Tovey slammed over another touchline conversion.
Tovey then missed a long-range penalty so it was 19-19 going into the final quarter before Benetton regained the lead through a second try from the impressive Halafihi.
Despite this score, Blues continued to dominate the second half and were rewarded with match-winning tries from Davies and Jones, with a late penalty from Tovey completing their comeback.
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