French champions Stade Francais took another decisive step towards the Heineken Cup quarter-finals as they compounded Welsh misery in this season's tournament.
Cardiff's emphatic defeat was the fifth successive reversal for a Welsh regional team following a four-game European whitewash last weekend.
And it effectively destroyed their hopes of progressing from Pool Six, leaving them a distant nine points behind group leaders Stade.
Cardiff's lineout was an embarrassment throughout the contest - they lost 10 on their own throw before half-time - and Stade predictably prospered.
Pressure is now bound to increase on Cardiff's beleaguered head coach David Young, and a chorus of boos at the final whistle summed up the frustration among a 7,000-strong Arms Park crowd.
Stade never threatened to hit top gear, but they effectively won the game by scoring two tries in five minutes from driven lineouts when Cardiff lock Craig Quinnell was in the sin-bin.
Stade knew a victory in Wales - they had failed on three previous Heineken Cup trips to the Principality - would give them a commanding advantage over Cardiff and group rivals Gloucester and Ulster.
Coach Fabien Galghie made changes following last weekend's win against Gloucester, restoring Italian international Mauro Bergamasco to flanker from centre, handing Raphael Poulin a start on the wing and replacing prop Rodrigo Roncero with Uruguayan World Cup forward Pablo Lemoine.
Cardiff, beaten by Ulster in Belfast a week ago, made one change, preferring scrum-half Richard Smith to Dean Dewdney, although Dewdney made his presence felt by scoring two second-half tries after he went on as a substitute wing.
Cardiff offered glimpses of quality in attack, notably through the adventurous Rhys Williams, but Stade had far too much power up front and composure in key areas.
Fly-half David Skrela, who finished with 15 points, landed a seventh-minute penalty to open the scoring, and although his opposite number Lee Thomas then levelled the scores, Stade ended a disappointing opening period in charge.
Argentinian international Gonzalo Quesada, sent on as a 37th-minute substitute, dropped a goal to edge the visitors in front and then they rocked Cardiff with a stunning solo try four minutes into injury-time.
Wing Julien Arias collected the ball well inside his own half, and duly prospered from a series of shambolic missed Cardiff tackles to sprint away and score in the corner.
Cardiff, despite their badly malfunctioning lineout, gave their supporters a glimmer of hope when Dewdney rounded off a crisp move two minutes after the restart, but Quinnell's yellow card proved significant in the overall equation.
With Quinnell kicking his heels on the touchline, Bergamasco powered over from close range, and before Cardiff could recover, Stade prop Sylvain Marconet touched down for his third Heineken Cup try this season.
A piece of Williams magic created Dewdney's second try, but Stade were not to be denied in their quest for a second successive bonus point victory which gave them a perfect 10 points out of 10.
Skrela booted further penalties in the 71st and 80th minutes, either side of a try for Quesada, who capitalised on a poor Cardiff clearance to touch down near the posts - and Skrela converted.
Stade will now prepare for back-to-back appointments with Ulster when rounds three and four of the Heineken Cup convene in early December, but Cardiff face difficult games against Gloucester, by which time it remains to be seen whether Young will still be in his job.