Leinster have tasted defeat for the first time in this season’s European Champions Cup.
They picked up a losing bonus point in a 24-18 defeat to Harlequins at the Stoop.
Tries from Nick Easter and Asaeli Tikoirotuma proved the difference for Quins, with six Ian Madigan penalties Leinster’s only outlet.
The sides meet again in six days’ time at the Aviva.
