There were seven tries in Leinster's 43-16 European Champions Cup win over Northampton Saints as they made it 10 victories from 10.
Eroni Sau's try proved decisive as Edinburgh saw off Pro14 Group B leaders Munster, while Ulster thrashed Scarlets on Friday.
Ospreys were no match for Saracens on Saturday, while Exeter Chiefs were among the other European Champions Cup winners.
Ireland centre Garry Ringrose was the star of the show as Leinster started their bid to regain the Champions Cup with a bonus-point win.
Munster were delighted to have Andrew Conway back in Pro14 action as he settled an all-Irish affair with Ulster.
After succumbing to a thrashing against Edinburgh in their previous match, Scarlets narrowly beat Cheetahs in Pro14.
Munster top Pro14 Conference B after their 28-12 victory over Ospreys, while Cardiff Blues were defeated 23-14 by Ulster.
Friday's Pro14 fixtures saw a trio of easy victories as the Cheetahs, Leinster and Connacht all won by big margins.
Ulster suffered a hammering in Bloemfontein, where wing Anthony Volmink scored three of nine tries for the Cheetahs.
Dave Kearney's hat-trick helped Leinster begin the defence of their Pro14 title with a win over Benetton Treviso.