Dan Biggar's Toulon struggle against Zebre as Cardiff thrash Brive
The 41-0 success was the first victory for a Welsh side in a European competition since December 2020, ending a 21-match winless streak.
Connacht also claimed bragging rights with a routine 22-8 win over Newcastle.
Both teams rotated their squads and despite a close first half, the Gallagher Premiership club were unable to add to their tally after the interval and returned across the Irish Sea with no points.
Wales fly-half Dan Biggar kicked a late conversion in Toulon’s 24-21 win at Zebre.
A thrilling battle between the Lions and Dragons in Johannesburg ended in a dramatic 31-31 draw in Pool B.
Lions also had their chance to take a full quota of points with Jordan Hendrikse sending a last-gasp penalty wide after Edwill van der Merwe’s brace had added to earlier scores by Giovani Lombard and Asenathi Ntlabakanye
In the other Pool B clash, Cheetahs edged out French hosts Pau by a 21-16 score.