All four Pro14 sides in European Rugby Champions Cup action on Saturday secured victories, three coming against French opposition.
Munster moved top of Pro14's Conference A after capitalising on Glasgow Warriors' defeat to in-form Benetton Treviso.
Munster ended a four-game losing streak against Leinster with a 26-17 triumph on Saturday, while Edinburgh retained the 1872 Cup.
Connacht scored four tries but still lost out to Leinster, who rallied from 17 points down to triumph in dramatic circumstances.
Saracens battled past Cardiff Blues to stay top of Pool 3, while Toulouse came out on top in an entertaining clash with Wasps.
After helping Ireland enjoy a dominant 2018, Johnny Sexton was named the World Rugby Player of the Year.
Leinster delivered a fantastic performance against the Ospreys, racking up 52 points as seven different players crossed for tries.
Sean O’Brien had surgery on his broken arm and will be out for between eight and 12 weeks, Leinster revealed on Monday.
Sean O'Brien suffered another injury blow on Saturday, but Ireland coach Joe Schmidt says he has the resilience to make a quick return.
Gethin Jenkins dragged a shot at goal wide after requiring assistance to keep the ball on the tee in a victorious final match.
Fergus McFadden faces a lengthy spell on the sidelines after suffering a high-grade tear of his hamstring in training.
Munster overturned a 14-point deficit to beat Glasgow Warriors thanks to Rory Scannell's monster penalty with the final play.
Maxime Medard's late try proved crucial as Toulouse beat European Champions Cup holders Leinster on Sunday.
Leinster accelerated out of sight in the second half of their European Champions Cup opener as Wasps were completely outclassed.
Leinster are five points clear at the top of Conference B after the defending champions beat Munster at the Aviva Stadium.
Leinster's Pro14 title defence continued with a fourth win in five, with Glasgow Warriors and the Ospreys matching that return on Saturday.