Leinster made it 10 wins from 10 to start the season as they routed Northampton Saints 43-16 in the European Champions Cup to move five points clear at the top of Pool 1.
The Irish province, beaten in last season's final by Saracens, ran in seven tries to beat Premiership leaders Saints, who came into this game having won both of their first two games in this competition.
Three Dan Biggar penalties, added to a try from Ahsee Tuala, meant Northampton led 16-14 with two minutes remaining in the first half.
However, Andrew Porter dotted down for Leinster's third try, following earlier scores from James Lowe and Rhys Ruddock, to ensure the visitors were leading 19-16 at the interval.
Northampton then failed to score a second-half point, while Cian Healy, Ross Byrne, Luke McGrath and Ed Byrne all crossed in Leinster's handsome victory.
Ulster moved top of Pool 3 as John Cooney's 79th-minute penalty earned them a 25-24 success over Harlequins.
Both sides scored three tries apiece, Elia Elia going over twice for Quins, but Cooney kept his cool from the 10-metre line to seal the win for Ulster.
Defending champions Saracens were beaten 10-3 by Munster to suffer their second loss in Pool 4.
Peter O'Mahony crossed for the game's only try in the 31st minute, with all the points scored prior to the interval, and the only sour moment for Munster came in the 82nd minute when Arno Botha was dismissed for dangerous play.
Teddy Thomas accounted for two of Racing 92's six tries in their 40-19 rout of Ospreys, who were left to rue Dan Evans' red card after just 37 seconds.
The full-back was given his marching orders for kicking Thomas in the face as he collected a high ball, and Ospreys never recovered.
Elsewhere, Lyon beat Benetton Treviso 28-0, while Glasgow Warriors edged past La Rochelle 27-24.