Cardiff fell to a disappointing BKT United Rugby Championship home defeat as the Emirates Lions flexed their forward muscle in difficult conditions.
The Blue and Blacks made an encouraging start and took the lead thanks to the boot of Jarrod Evans.
Cardiff enjoyed the majority of territory and possession in the opening 40 but could only cross the whitewash once - thanks to James Botham. A late penalty try in the Lions' favour meant only three points separated the sides at the break.
Cardiff made a bruising start to the encounter, using Taulupe Faletau and Lopeti Timani as battering rams and testing the Lions back-three with kicks into the swirling wind and rain.
Jarrod Evans booted the Blue and Blacks into a slender lead after nine minutes and the home side continued to hammer away.
Aled Summerhill and Rey Lee-Lo grew in prominence and Liam Belcher broke off the back of a stray Lions line out to burst into the red zone. It appeared a try was inevitable as Timani cut a razor-sharp inside line at pace but he was met on the try-line by two tacklers and lost possession.
Cardiff continued to enjoy the better of the encounter and controlled the territorial battle but they were unable to breach the Lions defence, often opting for attacking kicks to the corner.
Evans kept the scoreboard ticking with a second penalty on 23 minutes before Gianni Lombrd replied just before the half-hour mark.
Play was halted for some time on 33 minutes, following a heavy collision at the breakdown between Summerhill and Timani, the latter eventually getting to his feet to continue and the former departing for a HIA.
Mason Grady came on as a temporary replacement and his first act was to drill a kick into the Lions’ twenty-two, which was fumbled into touch by Sanele Nohamba.
From the ensuing line out, Cardiff set-up camp with Grady hitting it up from first phase. The ball was spread from left to right before a succession of pick and goes, which eventually saw Botham twist and turn his way over.
Evans added the simple extras for a 13-3 lead but they were dealt a set-back when an awkward bounce saw Tomos Williams clattered and a penalty conceded.
The ball was kicked to the corner and with the final play Sam Grove-White awarded a penalty try and sin-binned Faletau.
Cardiff spent the first ten minutes of the second-half defending their try-line and while they twice appeared to survive against the odds, the Lions made the pressure count with a PJ Botha try.
Lombard added the extras to give his side a 13-17 lead and Cardiff introduced the reinforcements with Uilisi Halaholo, Dmitri Arhip and Corey Domachowski called into action with Faletau also reintroduced.
However, Cardiff remained inside their twenty-two for long periods, with decisions going against them at an increasing frequency. That led to a third Lions try, which came in fortuitous circumstances.
While they had turned the screw, the ball was lost at the breakdown, however TMO replays showed it went backwards and Morne van den Berg was the quickest to react. Lombard converted from wide to give the visitors a commanding 13-24 lead.
It did not take Cardiff long to respond as they received a penalty of their own and went to the corner. Lions infringed to allow a second penalty and the pack rumbled over with Shane Lewis-Hughes dotting down.