Cardiff suffered their first defeat of the season as Leinster ran in a 29-5 victory at Dublin’s Laya Arena.
Corniel van Zyl made seven changes to his starting XV and the Welsh club were also dealt an injury blow with Wales great Taulupe Faletau pulling out before kick-off.
Faletau was replaced by Taine Basham who put in an outstanding individual performance.
Leinster scored five tries in total with Hugo Keenan, Jimmy O’Brien (twice), Jack Conan and Jamie Osborne touching down to secure a bonus point victory for the Irish province.
Mason Grady scored Cardiff’s only try in what was a spirited performance by the Welsh club despite the final scoreline.
Ireland full-back Keenan opened the scoring with a sensational individual try before Conan powered over from short-range soon after.
Leinster’s pack were in complete control as O’Brien touched down twice out wide.
Callum Sheedy caught the Leinster defence napping with a cross-field kick for Grady to score Cardiff’s only points.
Leinster led 22-5 at the break and Cardiff showed tremendous fight in the second-half.
It took the hosts 37 minutes of the second-half to score their first points as Osborne touched down to secure victory.
Leinster: Keenan; Kenny, Ringrose, J Osborne, J O’Brien; Prendergast, Coffey; Usanov, Sheehan (capt), Furlong, J McCarthy, Ryan, Deegan, Penny, Conan. Replacements: Kelleher, Dooley, Clarkson, Spicer, Ericson, Gunne, Gabriel, Henshaw.
Cardiff: Matty Young; Jacob Beetham, Harri Millard, Le Roux Malan, Mason Grady; Callum Sheedy, Aled Davies; Danny Southworth, Liam Belcher (capt), Javan Sebastian, Josh Mcally, Teddy Williams, Alex Mann, Dan Thomas, Taulupe Faletau. Replacements: Evan Lloyd, Rhys Barratt, Sam Wainwright, George Nott, Semisi Paea, Johan Mulder, Jarrod Evans, Steffan Emanuel